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问Autolayout编程
EN

Stack Overflow用户

提问于 2015-10-26 12:44:52

回答 3查看 540关注 0票数 0

我试图深入到汽车布局的深度，我对storyboard.Also的汽车布局有很好的了解，我也知道如何使用NSLayoutConstraint类。问题是:我有两个视图( redView和yellowView).From故事板，我已经在代码中设置了两个views.Now的约束，假设我想更改redView w.r.t的宽度-- yellowView.So的宽度--为此我使用了以下代码：

NSLayoutConstraint *layouts1 = [NSLayoutConstraint 
                               constraintWithItem:_redView 
                               attribute:NSLayoutAttributeWidth 
                               relatedBy:NSLayoutRelationEqual 
                               toItem:_yellowView 
                               attribute:NSLayoutAttributeWidth
                               multiplier:3.0f 
                               constant:0];
[self.view addConstraint:layouts1];

现在我运行代码，虽然我得到了预期的输出，但它在控制台上显示了“不可满足的约束”消息(因为设置了多个宽度)，.Now的问题是:我如何处理掉该消息？我尝试过几件事，但它们不是working.Here，这是我尝试过的：

我没有在storyboard.Instead中设置约束，我直接使用了下面的代码。
我试着用‘布局’的方法。

嗯，我可以用编程的方式编写整个自动布局代码，但是由于我们有通过故事板设置自动收费的特权，所以unnecessary.There必须是完全以某种方式以编程方式更新约束(设置在故事板中)，而不产生任何冲突。

ios

autolayout

回答 3

Stack Overflow用户

回答已采纳

发布于 2015-10-26 13:12:00

好吧，我明白我想要做的是什么--我已经在故事板中设置了约束，我需要删除这个宽度约束(在故事板中)，用一个新的do.As更新它--我刚刚创建了一个与constraint.SO宽度相同的IBOutlet，然后这段代码帮了我的忙：

[_yellowView removeConstraint:_myConstraints];//_myConstraints is the outlet

现在我没有面对任何problem.Thanks很多人:-)

票数 0

Stack Overflow用户

发布于 2015-10-27 10:44:45

当您想以编程方式编辑现有约束时，我是否正确地理解了您？即从故事板中设置的约束？

可以从约束创建IBOutlet，并以编程方式设置其constant-property。然后打电话给layotIfNeeded。

票数 1

Stack Overflow用户

发布于 2015-10-27 12:21:51

标记：-查找约束

- (NSLayoutConstraint *)myConstraintWithAttribute:(NSLayoutAttribute)attribute
{
    /* Find constraint with attribute in my constraints */
    __block NSLayoutConstraint *resultConstraint;
    [self.constraints enumerateObjectsUsingBlock:^(NSLayoutConstraint *constraint, NSUInteger idx, BOOL *stop)
     {
         //  DebugLog(@"constraint %@", constraint);
         if ([NSStringFromClass([NSLayoutConstraint class]) isEqualToString:NSStringFromClass([constraint class])])
         {
             if (constraint.firstAttribute == attribute || constraint.secondAttribute == attribute)
             {
                 resultConstraint = constraint;
                 *stop = YES;
             }
         }
     }];

    return resultConstraint;
}


- (NSLayoutConstraint *)superviewConstraintWithAttribute:(NSLayoutAttribute)attribute
{
    /* Find constraint with attribute in my superview's constraints */
    __block NSLayoutConstraint *resultConstraint;
    [self.superview.constraints enumerateObjectsUsingBlock:^(NSLayoutConstraint *constraint, NSUInteger idx, BOOL *stop)
     {
         if (constraint.firstItem == self && constraint.firstAttribute == attribute)
             //|| (constraint.secondItem == self && constraint.secondAttribute == attribute))
         {
             resultConstraint = constraint;
             *stop = YES;
         }
     }];

    return resultConstraint;
}


- (NSLayoutConstraint *)constraintWithAttribute:(NSLayoutAttribute)attribute
{
    /* Find constraint with attribute in my constraints */
    NSLayoutConstraint *resultConstraint = [self myConstraintWithAttribute:attribute];

    /* Find constraint with attribute in my superview's constraints */
    if (!resultConstraint)
    {
        resultConstraint = [self superviewConstraintWithAttribute:attribute];
    }
    return resultConstraint;
}


- (BOOL)removeConstraintWithAttribute:(NSLayoutAttribute)attribute
{
    NSLayoutConstraint *constraint = [self superviewConstraintWithAttribute:attribute];
    if (constraint)
    {
        [self.superview removeConstraint:constraint];
        return YES;
    }
    constraint = [self myConstraintWithAttribute:attribute];
    if (constraint)
    {
        [self removeConstraint:constraint];
        return YES;
    }
    return NO;
}

标记：-删除约束

- (void)removeMyConstraints
{
    /* Remove all my constraitns from superview */
    [self.superview removeConstraints:[self mySuperviewConstraints]];

    /* Remove my constraitns */

    [self removeConstraints:self.constraints];
}


- (NSArray *)mySuperviewConstraints
{
    NSMutableArray *mySuperviewConstraints = [NSMutableArray array];
    [self.superview.constraints enumerateObjectsUsingBlock:^(NSLayoutConstraint *constraint, NSUInteger idx, BOOL *stop)
     {
         if (constraint.firstItem == self || constraint.secondItem == self)
         {
             [mySuperviewConstraints addObject:constraint];
         }
     }];
    return mySuperviewConstraints;
}


- (void)removeMyConstraintsButKeepMySubviewConstraints
{
    /* Remove all my constraitns from superview */
    [self.superview removeConstraints:[self mySuperviewConstraints]];

    /* Remove my constraitns */

    [self removeConstraints:[self myConstraints]];
}


- (NSArray *)myConstraints
{
    NSMutableArray *myConstraints = [NSMutableArray array];
    [self.constraints enumerateObjectsUsingBlock:^(NSLayoutConstraint *constraint, NSUInteger idx, BOOL *stop)
     {
         if (constraint.firstItem == self && constraint.secondItem == nil)
         {
             [myConstraints addObject:constraint];
         }
     }];
    return myConstraints;
}

标记：-大小约束

- (void)addWidthConstraint:(CGFloat)width
{
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self
                                                                  attribute:NSLayoutAttributeWidth
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:nil
                                                                  attribute:0
                                                                 multiplier:1
                                                                   constant:width];
    [self addConstraint:constraint];
}

- (void)addWidthConstraintFromLabel:(UILabel *)label
                         withOffset:(CGFloat)offset
{
    NSDictionary *attributes = @{NSFontAttributeName : label.font};
    return [self addWidthConstraint:[label.text sizeWithAttributes:attributes].width + offset];
}

- (void)addHeightConstraint:(CGFloat)height
{
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self
                                                                  attribute:NSLayoutAttributeHeight
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:nil
                                                                  attribute:0
                                                                 multiplier:1
                                                                   constant:height];
    [self addConstraint:constraint];
}

- (void)addMaximumHeightConstraint:(CGFloat)maxHeight
{
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self
                                                                  attribute:NSLayoutAttributeHeight
                                                                  relatedBy:NSLayoutRelationLessThanOrEqual
                                                                     toItem:nil
                                                                  attribute:0
                                                                 multiplier:1
                                                                   constant:maxHeight];
    [self addConstraint:constraint];

}


- (void)addWidthConstraintFromImage:(UIImage *)image
{
    [self addWidthConstraint:image.size.width];
}


- (void)addHeightConstraintFromImage:(UIImage *)image
{
    [self addHeightConstraint:image.size.height];
}

马克：-中心违禁品

- (void)addCenterConstraint:(UIView *)view
            centerDirection:(NSLayoutAttribute)centerDirection
                     offset:(CGFloat)offset
{
    UIView *viewItem = (view) ? view : self.superview;
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self
                                                                  attribute:centerDirection
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:viewItem
                                                                  attribute:centerDirection
                                                                 multiplier:1
                                                                   constant:offset];
    [self.superview addConstraint:constraint];
}


- (void)addCenterXConstraint:(UIView *)view
{
    [self addCenterConstraint:view
              centerDirection:NSLayoutAttributeCenterX
                       offset:0];
}


- (void)addCenterYConstraint:(UIView *)view
{
    [self addCenterConstraint:view
              centerDirection:NSLayoutAttributeCenterY
                       offset:0];
}


- (void)addCenterXConstraint:(UIView *)view
                      offset:(CGFloat)offset
{
    [self addCenterConstraint:view
              centerDirection:NSLayoutAttributeCenterX
                       offset:offset];
}


- (void)addCenterYConstraint:(UIView *)view
                      offset:(CGFloat)offset
{
    [self addCenterConstraint:view
              centerDirection:NSLayoutAttributeCenterY
                       offset:offset];
}

标记：-边缘附加约束

- (void)addEdgeAttachConstraint:(UIView *)view
                       viewEdge:(NSLayoutAttribute)viewLayoutAttribute
                         offset:(CGFloat)offset
                           edge:(NSLayoutAttribute)layoutAttribute
{
    UIView *viewItem = (view) ? view : self.superview;

    /* Reverse offset for right side and bottom */
    CGFloat fixedOffset = offset;
    if (layoutAttribute == NSLayoutAttributeRight
        || layoutAttribute == NSLayoutAttributeBottom
        || layoutAttribute == NSLayoutAttributeTrailing)
    {
        fixedOffset = -offset;
    }

    /* Add contraint */
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self
                                                                  attribute:layoutAttribute
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:viewItem
                                                                  attribute:viewLayoutAttribute
                                                                 multiplier:1
                                                                   constant:fixedOffset];
    [self.superview addConstraint:constraint];
}




- (void)addLeftEdgeAttachConstraint:(UIView *)view
                             offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:NSLayoutAttributeLeft
                           offset:offset
                             edge:NSLayoutAttributeLeft];
}


- (void)addRightEdgeAttachConstraint:(UIView *)view
                              offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:NSLayoutAttributeRight
                           offset:offset
                             edge:NSLayoutAttributeRight];
}


- (void)addTopEdgeAttachConstraint:(UIView *)view
                            offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:NSLayoutAttributeTop
                           offset:offset
                             edge:NSLayoutAttributeTop];
}


- (void)addBottomEdgeAttachConstraint:(UIView *)view
                               offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:NSLayoutAttributeBottom
                           offset:offset
                             edge:NSLayoutAttributeBottom];
}




- (void)addLeftEdgeAttachConstraint:(UIView *)view
{
    [self addLeftEdgeAttachConstraint:view
                               offset:0];
}


- (void)addRightEdgeAttachConstraint:(UIView *)view
{
    [self addRightEdgeAttachConstraint:view
                                offset:0];
}


- (void)addTopEdgeAttachConstraint:(UIView *)view
{
    [self addTopEdgeAttachConstraint:view
                              offset:0];
}


- (void)addBottomEdgeAttachConstraint:(UIView *)view
{
    [self addBottomEdgeAttachConstraint:view
                                 offset:0];
}




- (void)addEdgeAttachConstraints:(UIView *)view
                      leftOffset:(CGFloat)leftOffset
                     rightOffset:(CGFloat)rightOffset
                       topOffset:(CGFloat)topOffset
                    bottomOffset:(CGFloat)bottomOffset
{
    [self addLeftEdgeAttachConstraint:view
                               offset:leftOffset];
    [self addRightEdgeAttachConstraint:view
                                offset:rightOffset];
    [self addTopEdgeAttachConstraint:view
                              offset:topOffset];
    [self addBottomEdgeAttachConstraint:view
                                 offset:bottomOffset];
}


- (void)addEdgeAttachConstraints:(UIView *)view
{
    [self addLeftEdgeAttachConstraint:view];
    [self addRightEdgeAttachConstraint:view];
    [self addTopEdgeAttachConstraint:view];
    [self addBottomEdgeAttachConstraint:view];
}

标记：-对不同边缘的边缘约束

- (void)addLeftEdgeAttachConstraint:(UIView *)view
                           viewEdge:(NSLayoutAttribute)viewLayoutAttribute
                             offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:viewLayoutAttribute
                           offset:offset
                             edge:NSLayoutAttributeLeft];
}


- (void)addRightEdgeAttachConstraint:(UIView *)view
                            viewEdge:(NSLayoutAttribute)viewLayoutAttribute
                              offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:viewLayoutAttribute
                           offset:offset
                             edge:NSLayoutAttributeRight];
}


- (void)addTopEdgeAttachConstraint:(UIView *)view
                          viewEdge:(NSLayoutAttribute)viewLayoutAttribute
                            offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:viewLayoutAttribute
                           offset:offset
                             edge:NSLayoutAttributeTop];
}


- (void)addBottomEdgeAttachConstraint:(UIView *)view
                             viewEdge:(NSLayoutAttribute)viewLayoutAttribute
                               offset:(CGFloat)offset
{
    [self addEdgeAttachConstraint:view
                         viewEdge:viewLayoutAttribute
                           offset:offset
                             edge:NSLayoutAttributeBottom];
}

标记：-尺寸附加约束

- (void)addSizeAndSuperviewAttachConstraints:(NSString *)sizeConstraint
                                 firstOffset:(CGFloat)firstOffset
                                secondOffset:(CGFloat)secondOffset
                                   direction:(NSString *)direction
{
    NSDictionary *viewDict = NSDictionaryOfVariableBindings(self);
    NSString *visualFormatString;

    if (sizeConstraint)
    {
        visualFormatString = [NSString stringWithFormat:@"%@:|-%f-[self(%@)]-%f-|", direction, firstOffset, sizeConstraint, secondOffset];
    }
    else
    {
        visualFormatString = [NSString stringWithFormat:@"%@:|-%f-[self]-%f-|", direction, firstOffset, secondOffset];
    }

    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:visualFormatString
                                                                   options:0
                                                                   metrics:0
                                                                     views:viewDict];
    [self.superview addConstraints:constraints];
}


- (void)addWidthAndSuperviewAttachConstraints:(NSString *)widthConstraint
                                   leftOffset:(CGFloat)leftOffset
                                  rightOffset:(CGFloat)rightOffset
{
    [self addSizeAndSuperviewAttachConstraints:widthConstraint
                                   firstOffset:leftOffset
                                  secondOffset:rightOffset
                                     direction:@"H"];
}


- (void)addHeightAndSuperviewAttachConstraints:(NSString *)heightConstraint
                                     topOffset:(CGFloat)topOffset
                                  bottomOffset:(CGFloat)bottomOffset
{
    [self addSizeAndSuperviewAttachConstraints:heightConstraint
                                   firstOffset:topOffset
                                  secondOffset:bottomOffset
                                     direction:@"V"];
}

标记：-行&列布局约束

- (void)addLayoutConstraintsForMySubviews:(NSArray *)views
                              firstOffset:(CGFloat)firstOffset
                             secondOffset:(CGFloat)secondOffset
                            betweenOffset:(NSString *)betweenOffset
                                direction:(NSString *)direction
                                equalSize:(BOOL)equalSize
{
    /* Create viewDict and visualFormatString */
    NSMutableString *visualFormatString = [[NSMutableString alloc] initWithFormat:@"%@:|-%.0f-", direction, firstOffset];
    NSMutableDictionary *viewDict = [[NSMutableDictionary alloc] init];
    [views enumerateObjectsUsingBlock:^(UIView *view, NSUInteger idx, BOOL *stop)
     {
         NSString *viewName = [NSString stringWithFormat:@"view%i", idx];
         [viewDict setObject:view
                      forKey:viewName];

         if (idx < [views count] - 1)
         {
             /* Add each view */
             if (betweenOffset) /* Add offset between view */
             {
                 /* Add equal size to prev view for all but index 0 */
                 if (equalSize && idx > 0)
                 {
                     NSString *prevViewName = [NSString stringWithFormat:@"view%i", idx - 1];
                     [visualFormatString appendFormat:@"[%@(==%@)]-%@-", viewName, prevViewName, betweenOffset];
                 }
                 else
                 {
                     [visualFormatString appendFormat:@"[%@]-%@-", viewName, betweenOffset];
                 }
             }
             else /* No offset between views */
             {
                 /* Add equal size to prev view for all but index 0 */
                 if (equalSize && idx > 0)
                 {
                     NSString *prevViewName = [NSString stringWithFormat:@"view%i", idx - 1];
                     [visualFormatString appendFormat:@"[%@(==%@)]", viewName, prevViewName];
                 }
                 else
                 {
                     [visualFormatString appendFormat:@"[%@]", viewName];
                 }
             }
         }
         else
         {
             /* Add equal size to prev view for all but index 0 */
             if (equalSize && idx > 0)
             {
                 NSString *prevViewName = [NSString stringWithFormat:@"view%i", idx - 1];
                 [visualFormatString appendFormat:@"[%@(==%@)]-%.0f-|", viewName, prevViewName, secondOffset];
             }
             else
             {
                 [visualFormatString appendFormat:@"[%@]-%.0f-|", viewName, secondOffset];
             }
         }
     }];

    //    DebugLog(@"viewDict %@", viewDict);
    //    DebugLog(@"visualFormatString %@", visualFormatString);

    /* Add constraints */
    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:visualFormatString
                                                                   options:0
                                                                   metrics:0
                                                                     views:viewDict];
    [self addConstraints:constraints];
}


- (void)addRowLayoutConstraintsForMySubviews:(NSArray *)subviews
                                  leftOffset:(CGFloat)leftOffset
                                 rightOffset:(CGFloat)rightOffset
                               betweenOffset:(NSString *)betweenOffset
                                  equalWidth:(BOOL)equalWidth
{
    [self addLayoutConstraintsForMySubviews:subviews
                                firstOffset:leftOffset
                               secondOffset:rightOffset
                              betweenOffset:betweenOffset
                                  direction:@"H"
                                  equalSize:equalWidth];
}


- (void)addColumnLayoutConstraintsForMySubviews:(NSArray *)subviews
                                      topOffset:(CGFloat)topOffset
                                   bottomOffset:(CGFloat)bottomOffset
                                  betweenOffset:(NSString *)betweenOffset
                                    equalHeight:(BOOL)equalHeight
{
    [self addLayoutConstraintsForMySubviews:subviews
                                firstOffset:topOffset
                               secondOffset:bottomOffset
                              betweenOffset:betweenOffset
                                  direction:@"V"
                                  equalSize:equalHeight];
}

标记：-行&列等尺寸布局约束

- (void)addEqualSizeLayoutConstraintsForMySubviews:(NSArray *)views
                                       firstOffset:(CGFloat)firstOffset
                                      secondOffset:(CGFloat)secondOffset
                                     betweenOffset:(NSString *)betweenOffset
                                         direction:(NSString *)direction
{
    /* Create viewDict and visualFormatString */
    NSMutableString *visualFormatString = [[NSMutableString alloc] initWithFormat:@"%@:|-%.0f-", direction, firstOffset];
    NSMutableDictionary *viewDict = [[NSMutableDictionary alloc] init];
    [views enumerateObjectsUsingBlock:^(UIView *view, NSUInteger idx, BOOL *stop)
     {
         NSString *viewName = [NSString stringWithFormat:@"view%i", idx];
         [viewDict setObject:view
                      forKey:viewName];

         if (idx < [views count] - 1)
         {
             if (betweenOffset)
             {
                 [visualFormatString appendFormat:@"[%@]-%@-", viewName, betweenOffset];
             }
             else
             {
                 [visualFormatString appendFormat:@"[%@(>=40)]", viewName];
             }
         }
         else
         {
             [visualFormatString appendFormat:@"[%@(>=40)]-%.0f-|", viewName, secondOffset];
         }
     }];


    //    DebugLog(@"viewDict %@", viewDict);

    /* Add constraints */
    NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[view0]-2-[view1(==view0)]-2-[view2(==view1)]-2-[view3(==view2)]-2-[view4(==view3)]-2-[view5(==view4)]-0-|"
                                                                   options:0
                                                                   metrics:0
                                                                     views:viewDict];
    [self addConstraints:constraints];
}


- (void)addRowLayoutEqualWidthConstraintsForMySubviews:(NSArray *)subviews
                                            leftOffset:(CGFloat)leftOffset
                                           rightOffset:(CGFloat)rightOffset
                                         betweenOffset:(NSString *)betweenOffset
{
    [self addEqualSizeLayoutConstraintsForMySubviews:subviews
                                         firstOffset:leftOffset
                                        secondOffset:rightOffset
                                       betweenOffset:betweenOffset
                                           direction:@"H"];
}

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/33346109

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