對於NSInvocation/invoke對，addTarget失敗

Question

我將字典值中的目標和操作傳遞給UIButtons。這工作正常，除非我嘗試並傳遞一個NSInvocation/invoke對。

// |self| is a member of |MyClass|, which declares selector |test| 

NSDictionary *button1Data = @{ @"selectorString" : NSStringFromSelector(@selector(test)), 
           @"target" : self }; 

[button1 addTarget:button1Data[@"target"] 
      action:NSSelectorFromString(button1Data[@"selectorString"]) 
    forControlEvents:UIControlEventTouchUpInside]; 

// button1 executes target fine 

NSInvocation *testInvocation = [NSInvocation invocationWithMethodSignature:[MyClass instanceMethodSignatureForSelector:@selector(test)]]; 
    testInvocation.selector = @selector(test); 
    testInvocation.target = self; 
    [testInvocation retainArguments]; 

NSDictionary *button2Data = @{ @"selectorString" : NSStringFromSelector(@selector(invoke)), 
             @"target" : testInvocation }; 

[button2 addTarget:button2Data[@"target"] 
      action:NSSelectorFromString(button2Data[@"selectorString"]) 
    forControlEvents:UIControlEventTouchUpInside]; 

// button2 executes gives exceptions 

button2的異常沒有寄存器轉儲。

我在忽略什麼？

Answer 1

addTarget:action:forControlEvents:不保留目標。你的NSInvocation對象是在函數內部本地創建的，當沒有人強有力地引用它時，它將在函數結束時被釋放。然後按鈕會發送一條消息給一個釋放的實例，導致各種不好的事情。