Question

我想要显示提醒，我的应用就会崩溃。这段代码很基本，我发现它没有任何问题。有人可以验证我做错了吗？

@implementation SampleClass
- (void) showAlert
{
UIAlertView *alert = [[UIAlertView alloc]
                      initWithTitle:@"Make an informed choice"
                      message:@"Descriptive text"
                      delegate:self
                      cancelButtonTitle:@"Cancel"
                      otherButtonTitles:@"OK", nil];
[alert show];
[alert release];    
}
@end

堆栈是：

0   libobjc.A.dylib                 0x3006bc98 objc_msgSend + 16
1   NESampleApp                     0x002ec5bc 0x1000 + 3061180
2   UIKit                           0x35584bee -[UIWindow _sendTouchesForEvent:] + 362
3   UIKit                           0x35584568 -[UIWindow sendEvent:] + 256
4   UIKit                           0x3556d30c -[UIApplication sendEvent:] + 292
5   UIKit                           0x3556cc4c _UIApplicationHandleEvent + 5084
6   GraphicsServices                0x35350e70 PurpleEventCallback + 660
7   CoreFoundation                  0x3599da90 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 20
8   CoreFoundation                  0x3599f838 __CFRunLoopDoSource1 + 160
9   CoreFoundation                  0x359a0606 __CFRunLoopRun + 514
10  CoreFoundation                  0x35930ebc CFRunLoopRunSpecific + 224
11  CoreFoundation                  0x35930dc4 CFRunLoopRunInMode + 52
12  GraphicsServices                0x35350418 GSEventRunModal + 108
13  GraphicsServices                0x353504c4 GSEventRun + 56
14  UIKit                           0x35597d62 -[UIApplication _run] + 398
15  UIKit                           0x35595800 UIApplicationMain + 664
16  NESampleApp                     0x0017d10c 0x1000 + 1556748
17  NESampleApp                     0x007d3720 0x1000 + 8202016

更新：将委托设置为nil后，我会获得更多信息以及崩溃：

<Error>: -[CALayer isTransformGestureInput]: unrecognized selector sent to instance 0xb4c8a0
<Error>: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CALayer isTransformGestureInput]: unrecognized selector sent to instance 0xb4c8a0'

Answer 1

尝试此而不是[alert show]

[alert performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:YES];

Answer 2

虽然这个答案可能无法解决这个特别（相当古老）的问题，但我确实来到这里是因为我有相同的症状。我的问题的答案是我没有传递“nil”作为otherButtonTitles上的第二项：@“OK”。

为：

UIAlertView *alert = [[UIAlertView alloc]
                      initWithTitle:@"Make an informed choice"
                      message:@"Descriptive text"
                      delegate:self
                      cancelButtonTitle:@"Cancel"
                      otherButtonTitles:@"OK"];

好：

UIAlertView *alert = [[UIAlertView alloc]
                      initWithTitle:@"Make an informed choice"
                      message:@"Descriptive text"
                      delegate:self
                      cancelButtonTitle:@"Cancel"
                      otherButtonTitles:@"OK", nil];

有趣的是，这只会导致我的设备崩溃，而不是iOS模拟器。

Answer 3

你的otherButtonTitles参数需要以nil结尾。

通常，采用可变数量参数的方法最后需要为nil。例如：

[NSArray arrayWithObjects:objA, objB, nil];

，在你的情况下：

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"error" message:@"message" delegate:self cancelButtonTitle:@"cancel" otherButtonTitles:@"otherbutton", nil];

Answer 4

你是否在一个区块内调用此方法？这将导致它崩溃。从您的区块内尝试：

[self performSelectorOnMainThread:@selector(showAlert) 
withObject:nil waitUntilDone:YES];

有同样的问题。这解决了它。答案采自：How do display a UIAlertView from a block on iOS?

应用程序在[UIAlertView show]崩溃

4 个答案: