当我点击它时，为什么这个按钮会崩溃我的应用程序？ UIButtion iPhone（ARC）

Question

每当我点击“newButton”我的应用程序崩溃。我正在使用自动引用计数。

编辑：刚试过这个在不同的应用程序，它的工作原理，但不工作在我自己的。

这里是我的代码：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    UIView *fullView = [[UIView alloc] initWithFrame:CGRectMake(0, -20, 320, 480)]; 
    fullView.backgroundColor = [UIColor blackColor]; 
    [[self view] addSubview:fullView]; 

    UIImage* blackButton =[[UIImage imageNamed:@"UIButtonBlack.png"]stretchableImageWithLeftCapWidth:10.0 topCapHeight:0.0]; 

    // Create button 
    UIButton *newButton = [[UIButton alloc] initWithFrame:CGRectMake(100, 100, 100, 30)]; 

    // Set button content alignment 
    newButton.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; 
    newButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter; 

    // Set button title 
    [newButton setTitle:@"Do Something" forState:UIControlStateNormal & UIControlStateHighlighted & UIControlStateSelected]; 
    // Set button title color 
    [newButton setTitleColor:[UIColor colorWithRed:255.0f/255.0 green:255.0f/255.0 blue:255.0f/255.0 alpha:1.0] forState:UIControlStateNormal & UIControlStateHighlighted & UIControlStateSelected]; 
    // Add the background image 
    [newButton setBackgroundImage:blackButton forState:UIControlStateNormal]; 
    // Add Events 
    [newButton addTarget:self action:@selector(showScanner:) forControlEvents:UIControlEventTouchUpInside]; 
    // in case the parent view draws with a custom color or gradient, use a transparent color 
    [newButton setBackgroundColor:[UIColor clearColor]]; 
    // Set titleShadowColor this way (apparently, titleLabel.shadowcolor does not work) 
    [newButton setTitleShadowColor:[UIColor colorWithRed:0.0f/255.0 green:0.0f/255.0 blue:0.0f/255.0 alpha:.75] forState:UIControlStateNormal & UIControlStateHighlighted & UIControlStateSelected]; 

    // Set button titleLabel properties 
    newButton.titleLabel.font = [UIFont fontWithName:@"PTSans-Bold" size:13.0]; 
    newButton.titleLabel.shadowOffset = CGSizeMake(1, 1);  

    [fullView addSubview:newButton]; 
} 

- (void)showScanner:(id)sender 
{ 
    NSLog(@"Do something…"); 
} 

Answer 1

你没有保持到您的视图控制器的引用。你要么需要使用

• 一个标准的iOS视图控制器经理喜欢的UITabBarController或UINavigationController的显示你的意见
• 保留您从打开它的类中的一个引用（在一个实例变量）这种视图控制器。

请注意，如果您要在ARC关闭的情况下重新编写此代码，则会出现内存泄漏，而不是崩溃。

问题是，从视图中所有对视图控制器的引用都是弱引用，这意味着它们不保留控制器*。因此，在您的加载代码中，ARC在您创建并访问其视图后释放视图控制器，并且它已经消失。

在您的应用程序中，您应该跟踪所有视图控制器，并通过它们访问其视图。像UINavigationController这样的东西为你做。

*这是因为视图控制器被认为拥有视图的所有权，并且如果视图控制器保留了视图并且视图保留了视图控制器，那么会有一个保留循环，并且它们都不会被发布。

Answer 2

我相信UIControlState的不能&（或|）在一起，因为根据UIControl Reference Docs：

控制可以有一次超过一个国家。

尝试他们分离出这样的：

// Set button title 
[newButton setTitle:@"Do Something" forState:UIControlStateNormal]; 
[newButton setTitle:@"Do Something" forState:UIControlStateHighlighted]; 
[newButton setTitle:@"Do Something" forState:UIControlStateSelected]; 

// Set button title color 
[newButton setTitleColor:[UIColor colorWithRed:255.0f/255.0 green:255.0f/255.0 blue:255.0f/255.0 alpha:1.0] forState:UIControlStateNormal]; 
[newButton setTitleColor:[UIColor colorWithRed:255.0f/255.0 green:255.0f/255.0 blue:255.0f/255.0 alpha:1.0] forState:UIControlStateHighlighted]; 
[newButton setTitleColor:[UIColor colorWithRed:255.0f/255.0 green:255.0f/255.0 blue:255.0f/255.0 alpha:1.0] forState:UIControlStateSelected]; 

// Add the background image 
[newButton setBackgroundImage:blackButton forState:UIControlStateNormal]; 

// Add Events 
[newButton addTarget:self action:@selector(showScanner:) forControlEvents:UIControlEventTouchUpInside]; 

// in case the parent view draws with a custom color or gradient, use a transparent color 
[newButton setBackgroundColor:[UIColor clearColor]]; 

// Set titleShadowColor this way (apparently, titleLabel.shadowcolor does not work) 
[newButton setTitleShadowColor:[UIColor colorWithRed:0.0f/255.0 green:0.0f/255.0 blue:0.0f/255.0 alpha:.75] forState:UIControlStateNormal]; 
[newButton setTitleShadowColor:[UIColor colorWithRed:0.0f/255.0 green:0.0f/255.0 blue:0.0f/255.0 alpha:.75] forState:UIControlStateHighlighted]; 
[newButton setTitleShadowColor:[UIColor colorWithRed:0.0f/255.0 green:0.0f/255.0 blue:0.0f/255.0 alpha:.75] forState:UIControlStateSelected]; 

// Set button titleLabel properties 
newButton.titleLabel.font = [UIFont fontWithName:@"PTSans-Bold" size:13.0]; 
newButton.titleLabel.shadowOffset = CGSizeMake(1, 1); 

---

它可能会崩溃，因为button应该是newButton。

更改此：

[button setTitleShadowColor:[UIColor colorWithRed:0.0f/255.0 green:0.0f/255.0 blue:0.0f/255.0 alpha:.75] forState:UIControlStateNormal & UIControlStateHighlighted & UIControlStateSelected]; 

要这样：

[newButton setTitleShadowColor:[UIColor colorWithRed:0.0f/255.0 green:0.0f/255.0 blue:0.0f/255.0 alpha:.75] forState:UIControlStateNormal & UIControlStateHighlighted & UIControlStateSelected];