设置UIButton的目标

我想，当以这种方式被压buttonCancel调用一个方法：设置UIButton的目标

+ (DejalActivityView *)activityViewForView:(UIView *)addToView withLabel:(NSString *)labelText width:(NSUInteger)aLabelWidth; 
{ 
// Immediately remove any existing activity view: 
if (dejalActivityView) 
    [self removeView]; 

// Remember the new view (so this is a singleton): 
dejalActivityView = [[self alloc] initForView:addToView withLabel:labelText width:aLabelWidth]; 

buttonCancel = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
[buttonCancel addTarget:self 
       action:@selector(callCancelAlert:) 
     forControlEvents:UIControlEventTouchDown]; 
[buttonCancel setTitle:@"Cancel upload" forState:UIControlStateNormal]; 
buttonCancel.frame = CGRectMake(250, 560, 300, 40); 
[addToView addSubview:buttonCancel]; 
[buttonCancel setImage:[UIImage imageNamed:@"socialize-navbar-bg.png"] forState:UIControlStateNormal]; 

return dejalActivityView; 
}

和

-(IBAction)callCancelAlert:(id)sender{ 

UIAlertView *alert = [[UIAlertView alloc] 
         initWithTitle: @"Announcement" 
         message: @"It turns out that you are playing Addicus!" 
         delegate: nil 
         cancelButtonTitle:@"OK" 
         otherButtonTitles:nil]; 
[alert show]; 
//[alert release]; 
}

我收到此错误的方法：

“NSInvalidArgumentException '，原因：'+ [DejalBezelActivityView callCancelAlert：]：无法识别的选择器发送到类0x3184e4' * F IRST扔调用堆栈：（0x327862a3 0x3a61f97f 0x32789ca3 0x32788531 0x326dff68 0x346790c5 0x34679077 0x34679055 0x3467890b 0x3467859b 0x345a1523 0x3458e801 0x3458e11b 0x362805a3 0x362801d3 0x3275b173 0x3275b117 0x32759f99 0x326ccebd 0x326ccd49 0x3627f2eb 0x345e2301 0x39445 0x3aa56b20）的libC++ abi.dylib：终止叫做抛出异常

而且该应用程序崩溃。

来源

2013-03-11 Alessandro

是'buttonCancel'a伊娃？ – limon 2013-03-11 18:48:59

没有它的UIButton * buttonCancel;并在第一个报告的方法之前创建 – Alessandro 2013-03-11 18:50:11

您的第一个方法是类方法（+）而不是实例方法（ - ），因此您处于Class上下文中。

当你写

[buttonCancel addTarget:self 
       action:@selector(callCancelAlert:) 
     forControlEvents:UIControlEventTouchDown];

自点而不是一个类的实例（例如通过创建或Alloc &初始化消息），但类本身。

由于在相同的方法，你的Alloc的DejalActivityView一个实例，你应该这样做：

[buttonCancel addTarget:dejalActivityView 
       action:@selector(callCancelAlert:) 
     forControlEvents:UIControlEventTouchDown];

来源

2013-03-11 18:54:34

设置UIButton的目标

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