在類別中實現UIAlertView委託方法

Question

我嘗試實現處理uialertview的viewcontroller類別。它需要實現-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex，如果viewcontroller還需要顯示警報視圖，不要搞砸。爲此，我將uialertview的委託設置爲類別內的虛擬對象而不是自我。但是當alertview中的其中一個按鈕被點擊時，我的應用程序崩潰exc_bad_access。下面的代碼有什麼問題？

//Dummy handler .h 

@interface dummyAlertViewHandler : NSObject <UIAlertViewDelegate> 

@property (nonatomic, weak) id delegate; 

//.m 
-(id) initWithVC:(id) dlg 
{ 
    self = [super init]; 
    if (self != nil) 
    { 
     self.delegate = dlg; 
    } 
    return self; 
} 

-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex 
{ 
    if (buttonIndex == 1) 
    { 
     [self mainMenuSegue]; //There is no problem with the method 
    } 
} 

//Category .h 
#define ALERT_VIEW_DUMMY_DELEGATE_KEY "dummy" 
@property (nonatomic, strong) id dummyAlertViewDelegate; 

//Category .m 
@dynamic dummyAlertViewDelegate; 

- (void)setDummyAlertViewDelegate:(id)aObject 
{ 
    objc_setAssociatedObject(self, ALERT_VIEW_DUMMY_DELEGATE_KEY, aObject, OBJC_ASSOCIATION_ASSIGN); 
} 

- (id)dummyAlertViewDelegate 
{ 
    id del = objc_getAssociatedObject(self, ALERT_VIEW_DUMMY_DELEGATE_KEY); 

    if (del == nil) 
    { 
     del = [[dummyAlertViewHandler alloc] initWithVC:self]; 
     self.dummyAlertViewDelegate = del; 
    } 

    return del; 
} 

-(void) mainMenuSegueWithConfirmation 
{ 
    UIAlertView *ruSure = [[UIAlertView alloc] initWithTitle:@"Confirm leave" 
message:@"Are you sure you want to leave this game?" 
delegate:self.dummyAlertViewDelegate 
cancelButtonTitle:@"No" 
otherButtonTitles:@"Yes", nil]; 

    [ruSure show]; 
} 

Answer 1

你的問題是這樣的一行：

objc_setAssociatedObject(self, ALERT_VIEW_DUMMY_DELEGATE_KEY, aObject, OBJC_ASSOCIATION_ASSIGN); 

具體的OBJC_ASSOCIATION_ASSIGN使你的相關物品不予保留。爲您設計在所有的工作，你將需要改變，要OBJC_ASSOCIATION_RETAIN，像這樣：

objc_setAssociatedObject(self, ALERT_VIEW_DUMMY_DELEGATE_KEY, aObject, OBJC_ASSOCIATION_RETAIN);