iOS 8 & Xcode 6：UIAlertView取消時不回調alertViewCancel:

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在做UIAlertView取消操作時，發現委託函數alertViewCancel:並不被調用，只好在alertView: didDismissWithButtonIndex:中進行判斷。

 1 @interface DateViewController () <UIAlertViewDelegate> 2 @property (weak, nonatomic) IBOutlet UIDatePicker *datePicker; 3  4 @end 5  6 @implementation DateViewController 7  8 - (void)viewDidLoad { 9     [super viewDidLoad];10     NSDate *now = [NSDate date];11     [self.datePicker setDate:now animated:NO];12 }13 14 - (void)didReceiveMemoryWarning {15     [super didReceiveMemoryWarning];16     // Dispose of any resources that can be recreated.17 }18 19 - (IBAction)buttonPress:(UIButton *)sender {20     NSDate *selectedDate = self.datePicker.date;21     NSDateFormatter *fmt = [[NSDateFormatter alloc] init];22     fmt.dateFormat = @"yyyy - MM - dd";23 24     NSString *string = [NSString stringWithFormat:@"You selecte %@", [fmt stringFromDate:selectedDate]];25     UIAlertView *view = [[UIAlertView alloc] initWithTitle:@"Date Picker"26                                                    message:string27                                                   delegate:self28                                          cancelButtonTitle:@"Cancel"29                                          otherButtonTitles:@"OK", nil];30     [view show];31 }32 33 - (void)alertViewCancel:(UIAlertView *)alertView {34     NSLog(@"View canceled.");35 }36 37 - (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {38     NSLog(@"buttonIndex = %zi", buttonIndex);39 }40 41 @end

日誌輸出如下，取消按鈕序號為0，其他按鈕序號按添加次序遞增。

iOS 8 & Xcode 6：UIAlertView取消時不回調alertViewCancel: