UITextView firstRectForRange返回错误帧

Question

编辑

简单的解决方案是将任何帧计算从viewDidLoad移到viewDidAppear:

我很难让下面的代码正常工作

该代码返回给定NSRange在UITextView中的第一个帧。

如果没有换行，它就能工作，但是当我在UITextView中添加换行时，我会得到一些奇怪的行为。

@implementation UITextView (TextFrame)

- (CGRect)frameOfTextRange:(NSRange)range {
    UITextPosition *beginning = self.beginningOfDocument;
    UITextPosition *start = [self positionFromPosition:beginning offset:range.location];
    UITextPosition *end = [self positionFromPosition:start offset:range.length];
    UITextRange *textRange = [self textRangeFromPosition:start toPosition:end];
    CGRect rect = [self firstRectForRange:textRange];

    return [self convertRect:rect fromView:self.textInputView];
}

@end

@implementation DetailViewController

- (void)viewDidLoad 
{
    [super viewDidLoad];
   if (self.searchString) {
        CGRect rect = [self.textView frameOfTextRange:[self.textView.text rangeOfString:self.searchString]];
        ...
    }
}

Answer 1

很明显，firstRectForRange:似乎不在viewDidLoad工作

将计算从viewDidLoad转移到viewDidAppear: 解决了问题

旧码

- (void)viewDidLoad 
{
    [super viewDidLoad];

    if (self.searchString) {
        CGRect rect = [self.textView frameOfTextRange:[self.textView.text rangeOfString:self.searchString]];
        [self.textView scrollRangeToVisible:[self.textView.text rangeOfString:self.searchString]];
        UIView *markerView = [[UIView alloc] initWithFrame:rect];
        markerView.backgroundColor = [UIColor colorWithRed:0.810 green:0.735 blue:0.000 alpha:0.660];
        [self.textView addSubview:markerView];
        _searchString = nil;
    }
}

新代码和工作代码

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    if (self.searchString) {
        CGRect rect = [self.textView frameOfTextRange:[self.textView.text rangeOfString:self.searchString]];
        [self.textView scrollRangeToVisible:[self.textView.text rangeOfString:self.searchString]];
        UIView *markerView = [[UIView alloc] initWithFrame:rect];
        markerView.backgroundColor = [UIColor colorWithRed:0.810 green:0.735 blue:0.000 alpha:0.660];
        [self.textView addSubview:markerView];
        _searchString = nil;
    }
}

Answer 2

我找到了下面的解决方案。不使用只返回一个rect的firstRectForRange:，而是使用selectionRectsForRange:，然后遍历所有rect并使用CGRectUnion组合它们。

- (CGRect)frameOfTextRange:(NSRange)range
{
   UITextPosition *beginning = self.beginningOfDocument;
   UITextPosition *start = [self positionFromPosition: beginning offset: range.location];
   UITextPosition *end = [self positionFromPosition: start offset: range.length];

   UITextRange *textRange = [self textRangeFromPosition: start toPosition: end];

   CGRect  rect = CGRectZero;

   NSArray *selectionRects = [self selectionRectsForRange: textRange];

   for (UITextSelectionRect *selectionRect in selectionRects)
   {
      rect = CGRectUnion(rect, selectionRect.rect);
   }

   return rect;
}

Answer 3

可以强制self.textView确保在以下情况下立即进行布局：

[self.textView.layoutManager ensureLayoutForTextContainer:self.textView.textContainer];

将其放置在frameOfTextRange:电话前将使您正确地重新定位。

当然，您可以在frameOfTextRange:方法中调用它：

- (CGRect)frameOfTextRange:(NSRange)range {
    [self.layoutManager ensureLayoutForTextContainer:self.textContainer];
    ...

这使得可以安全地从任何地方调用frameOfTextRange:方法。