ios - UILabel 导致应用程序在添加到 View 时崩溃(仅限 Xcode 6 和 iOS 8)

Question

我已将我的项目转换到 Xcode 6 以便为 iOS 8 构建。但是，一个特定的 UILabel 导致应用程序在添加到 View 层次结构时崩溃。这是我收到的唯一错误日志:

-[MyViewController _contentInsetsFromFonts]: unrecognized selector sent to instance     0x16d90da0

我无法在项目的任何位置找到 contentInsetsFromFonts 方法。此外，我什至无法在网上的任何地方找到它的引用资料，包括 Apple 的文档。我没有为此 UIViewController 使用 NIB，因此 UI 是在 loadView 方法中构建的:

- (void)loadView {
    UIImage *trackImage = [UIImage imageNamed:@"sliderTrack.png"];
    sliderBackground = [[UIImageView alloc] initWithImage:trackImage];
    UIView *view = [[UIView alloc] initWithFrame:sliderBackground.frame];
    [view addSubview:sliderBackground];

    slider = [[UISlider alloc] initWithFrame:sliderBackground.frame];
    CGRect sliderFrame = slider.frame;
    sliderFrame.size.width -= 46; 
    slider.frame = sliderFrame;
    slider.center = sliderBackground.center;
    slider.backgroundColor = [UIColor clearColor];
    [slider setMinimumTrackImage:[UIImage imageNamed:@"sliderMaxMinTrackImage.png"] forState:UIControlStateNormal];
    [slider setMaximumTrackImage:[UIImage imageNamed:@"sliderMaxMinTrackImage.png"] forState:UIControlStateNormal];
    UIImage *thumbImage = [UIImage imageNamed:@"cancel-slider.png"];
    [slider setThumbImage:thumbImage forState:UIControlStateNormal];
    slider.minimumValue = 0.0;
    slider.maximumValue = 1.0;
    slider.continuous = YES;
    slider.value = 0.0;

    // Set the slider action methods
    [slider addTarget:self 
           action:@selector(sliderUp:) 
     forControlEvents:UIControlEventTouchUpInside];
    [slider addTarget:self 
           action:@selector(sliderDown:) 
     forControlEvents:UIControlEventTouchDown];
    [slider addTarget:self 
           action:@selector(sliderChanged:) 
     forControlEvents:UIControlEventValueChanged];    

    NSString *labelText = @"label text";
    UIFont *labelFont;
    NSString *osVersion = [[UIDevice currentDevice] systemVersion];
    if ([osVersion floatValue] >= 7.0) {
        labelFont = [UIFont systemFontOfSize:22.0];

    } else {
        labelFont = [UIFont systemFontOfSize:24.0];
    }

    CGSize labelSize = [labelText sizeWithAttributes:[NSDictionary dictionaryWithObjectsAndKeys:labelFont, NSFontAttributeName, nil]];

    label = [[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, labelSize.width, labelSize.height)];

    CGFloat labelHorizontalCenter = slider.center.x + (thumbImage.size.width / 2);
    label.center = CGPointMake(labelHorizontalCenter, slider.center.y);

    // Set other label attributes and add it to the view
    label.textColor = [UIColor whiteColor];
    label.textAlignment = NSTextAlignmentCenter;
    label.backgroundColor = [UIColor clearColor];
    label.font = labelFont;
    label.text = labelText;

    [view addSubview:label];

    [view addSubview:slider];

    label.layer.delegate = self;

    self.view = view;
}

应用程序不会在 [view addSubview:label] 处崩溃；它在 loadView 方法返回后崩溃。

Answer 1

来自 the UIView documentation :

Never change the delegate of this layer object.

删除这一行:

label.layer.delegate = self;

无论您想在这里完成什么，都需要以另一种方式完成。