添加Alertview與在圖形頁面

Question

林按壓位置的座標有MapView的。我加入這個作爲視圖控制器的看法子視圖。我在viewDidLoad中下面的代碼：

[self.view addSubview:mapView]; 
    UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(mapLongPress:)]; 
    longPressGesture.minimumPressDuration = 2; 
    [mapView addGestureRecognizer:longPressGesture]; 
    [longPressGesture release]; 

而且，

- (void)mapLongPress:(UILongPressGestureRecognizer *)gestureRecognizer{ 
    NSLog(@"Gesture"); 
    if(gestureRecognizer.state == UIGestureRecognizerStateBegan){ 
     CGPoint touchLocation = [gestureRecognizer locationInView:mapView]; 

     CLLocationCoordinate2D coordinate; 
     coordinate = [mapView convertPoint:touchLocation toCoordinateFromView:mapView]; 

這些我從計算器得到。但其沒有工作..難道我需要做的事情更多的是什麼？

嘗試增加 [self.view addSubview:mapView];後 [mapView addGestureRecognizer:longPressGesture];

Answer 1

UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(mapLongPress:)]; 
longPressGesture.minimumPressDuration = 2; 
longPressGesture.delegate = self; 
[self.mapView addGestureRecognizer:longPressGesture]; 
[self.view addSubview:mapView]; 
[longPressGesture release]; 

Answer 2

只需添加UIGestureRecognizerDelegate到視圖控制器，做由我給上面的代碼！

Answer 3

試試這個：

UILongPressGestureRecognizer *lpgr = [[UILongPressGestureRecognizer alloc] 
             initWithTarget:self action:@selector(mapLongPress:)]; 
lpgr.minimumPressDuration = 2.0; 

[self.mapView addGestureRecognizer:lpgr]; 

這是使用ARC，所以我不知道是否應該在這一刻釋放手勢現在。嘗試它而不釋放它，然後嘗試釋放它。看看是否會影響手勢。