实现UIPopoverBackgroundView子类时的混淆异常

Question

我按照以下方式实现了这个类：

#import "JKBackgroundView.h"

@implementation JKBackgroundView

static CGFloat jkArrowBase = 26.0;
static CGFloat jkArrowHeight = 16.0;

// Background image insets
static CGFloat jkBackgroundTopInset = 68.0f;
static CGFloat jkBackgroundLeftInset = 16.0f;
static CGFloat jkBackgroundBottomInset = 16.0f;
static CGFloat jkBackgroundRightInset = 34.0f;

// Content view insets
static CGFloat jkContentTopInset = 40.0f;
static CGFloat jkContentLeftInset = 6.0f;
static CGFloat jkContentBottomInset = 8.0f;
static CGFloat jkContentRightInset = 7.0f;

+(CGFloat)arrowBase {
    return jkArrowBase;
}

-(UIPopoverArrowDirection)arrowDirection {
    return UIPopoverArrowDirectionUp;
}

-(CGFloat)arrowOffset {
    return 0.0f;
}

+(CGFloat)arrowHeight {
    return jkArrowHeight;
}

+(UIEdgeInsets)contentViewInsets {
    return UIEdgeInsetsMake(jkContentTopInset, jkContentLeftInset, jkContentBottomInset, jkContentRightInset);
}

-(void)drawRect:(CGRect)rect {
    UIEdgeInsets popoverInsets = UIEdgeInsetsMake(jkBackgroundTopInset, jkBackgroundLeftInset, jkBackgroundBottomInset, jkBackgroundRightInset);
    UIImage *popoverImage = [[UIImage imageNamed:@"popover_stretchable.png"] resizableImageWithCapInsets:popoverInsets];
    [popoverImage drawInRect:rect];
}

-(id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor clearColor];
    }
    return self;
}

-(void)setArrowDirection:(UIPopoverArrowDirection)arrowDirection {
    // Do nothing
}

@end

我使用以下代码将其添加到我的UIPopoverView (而不是子类)中：

_logoutPopover.popoverBackgroundViewClass = [JKBackgroundView class];

但是，当我运行该项目时，会收到如下疯狂的错误消息：

*由于“NSInternalInconsistencyException”异常终止应用程序，原因：‘-UIPopoverBack背景视图l’必须由子类实现。‘

有人知道它认为我没有实现什么方法吗？这似乎只是一堆胡言乱语。谢谢!

编辑看起来我忘了实现setArrowOffset：。在添加了这个之后它就能工作了。苹果的错误信息被弄错了。

Answer 1

根据UIPopoverBackgroundView文档，还需要为UIPopoverBackgroundView中的属性(即arrowDirection和arrowOffset)实现setter。您刚刚在您的实现中获得了getter。