UILabel导致应用程序崩溃时添加到视图（仅Xcode 6和iOS 8） [英] UILabel causes app to crash when added to view (Xcode 6 and iOS 8 only)

问题描述

我已经将我的项目转换到Xcode 6为了构建为iOS 8.然而，一个特定的UILabel导致应用程序崩溃时，它被添加到视图层次结构。这是我收到的唯一错误日志：

   -  [MyViewController _contentInsetsFromFonts]：无法识别的选择器发送到实例0x16d90da0 
  

我在项目中找不到 contentInsetsFromFonts 。此外，我甚至不能在任何地方找到它的参考，包括苹果的文档。我不为这个UIViewController使用NIB，所以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; 
 
 //设置滑块动作方法
 [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 labelHorizo​​ntalCenter = slider.center.x +（thumbImage.size.width / 2）; 
 label.center = CGPointMake（labelHorizo​​ntalCenter，slider.center.y）; 
 
 //设置其他标签属性并将其添加到视图
 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; 
} 
  

应用程序不会崩溃 [view addSubview： label] ; loadView 方法返回时会崩溃。

解决方案

=https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIView_Class/UIView/UIView.html#//apple_ref/occ/instp/UIView/layer> UIView 文档：

不要更改此图层对象的委托。

删除此行：

  label.layer。 delegate = self; 
  

无论你想在这里完成什么，你都需要以另一种方式。 p>

I have transitioned my project to Xcode 6 in order to build for iOS 8. However, a particular UILabel is causing the app to crash when it is added to the view hierarchy. This is the only error log I receive:

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

I have been unable to locate the contentInsetsFromFonts method anywhere in my project. Additionally, I have not even been able to find a reference for it anywhere online, including Apple's documentation. I am not using a NIB for this UIViewController so the UI is built in the loadView method:

- (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;
}

The app does not crash at [view addSubview:label]; it crashes after the loadView method returns.

解决方案

From the UIView documentation:

Never change the delegate of this layer object.

Delete this line:

label.layer.delegate = self;

Whatever you're trying to accomplish here, you'll need to do in another way.

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