iOS 长按不适用于 map

Question

我试图在长按以在该位置周围绘制覆盖图后获取该位置。但是，我设置的长按 Action 并没有触发。

-(void) viewWillAppear:(BOOL)animated{
[super viewWillAppear:YES];

//add the long press options

//single finger long press
UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(getMapCoordinateFromTouch:)];
[longPressGesture setNumberOfTouchesRequired:1];
longPressGesture.delegate = self;
[self.mapview addGestureRecognizer:longPressGesture];

//double finger long press
UILongPressGestureRecognizer *doubleLongPressGesture = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(removeBoundry:)];
[doubleLongPressGesture setNumberOfTouchesRequired:2];
doubleLongPressGesture.delegate = self;
[self.mapview addGestureRecognizer:doubleLongPressGesture];

这是它调用的函数

-(void)getMapCoordinateFromTouch:(UILongPressGestureRecognizer *) gesture{
if(gesture.state == UIGestureRecognizerStateBegan){
    CGPoint touchlocation = [gesture locationInView:self.mapview];
    pressedloc = [self.mapview convertPoint:touchlocation toCoordinateFromView:self.mapview];
    [self createBundarywithRadius:.1];    
}

Answer 1

很酷，所以你的 mapview 对象是 nil。

如果您使用的是界面构建器，那么您还没有将您的属性附加到可视组件。这是基本的东西，有很多关于如何做这种事情的教程。

简而言之，您应该已经有了类似的东西:

@property (nonatomic, weak) IBOutlet MKMapView *mapview;

这没有连接到界面构建器组件，那是你的问题!

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