如何获取UIImageView的边缘以捕捉到屏幕边缘（超级视图）？

Question

我不希望任何人为我编写代码。我只是在朝着框架和/或使用方法的正确方向寻求推动。我想要做的是，在iOS Swift中，允许用户选择一张照片并将其放置在屏幕上。我已经有那部分工作。我也有它的工作，你可以通过拖动图像来定位它，并捏合使其变大或变小。然而，“棘手”的部分是以下...当边缘（或边缘）接近超级视图（屏幕）的框架时，我希望ImageView能够“捕捉”到边缘的位置。基本上，我希望图像的边缘被“磁性”吸引到屏幕的边缘。我不太确定哪种方法组合最适合完成这一点。任何建议感激。

编辑： 这里是我迄今为止...

class AdjustableImageView: UIImageView { 

    var parent:ViewController! 

    // last location for view 
    var lastSavedLocation = CGPointZero 

    override init(frame: CGRect) { 
     super.init(frame: frame) 

     // add pan gesture to view 
     let panGesture = UIPanGestureRecognizer(target: self, action: "handlePanGesture:") 
     let longPressGesture = UILongPressGestureRecognizer(target: self, action: "handleLongPress:") 
     let pinchGesture = UIPinchGestureRecognizer(target: self, action: "pinchRecognized:") 
     self.addGestureRecognizer(panGesture) 
     self.addGestureRecognizer(longPressGesture) 
     self.addGestureRecognizer(pinchGesture) 
     self.userInteractionEnabled = true 
    } 

    required init?(coder aDecoder: NSCoder) { 
     fatalError("init(coder:) has not been implemented") 
    } 

    func pinchRecognized(pinch: UIPinchGestureRecognizer) { 
     // change view scale based on pinch 
     self.transform = CGAffineTransformScale(self.transform, pinch.scale, pinch.scale) 
     pinch.scale = 1.0 
    } 

    func handlePanGesture(gesture: UIPanGestureRecognizer) { 
     // find translation in main view 
     let newTranslation = gesture.translationInView(self.superview) 

     // set current object to new position 
     self.center = CGPointMake(self.lastSavedLocation.x + newTranslation.x , self.lastSavedLocation.y + newTranslation.y) 
    } 

    // detect touch for the current view and change last save postion 
    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) { 

     // move touched view to front. 
     self.superview?.bringSubviewToFront(self) 

     self.layer.borderColor = UIColor.greenColor().CGColor 
     self.layer.borderWidth = 2 

     // save view location 
     self.lastSavedLocation = self.center 

     parent.imageSelected(self) 
    } 

    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) { 
     self.layer.borderWidth = 0 
    } 
} 

Answer 1

的声音，我想要的财产以后像则hitTest。

Hittest

所以，我想你不会想和拖放工作。尽快触发一个marge（5-10或15dp/px）触发器，你锁定图像=>停止拖动并以编程方式定位视图...我没有测试这个，但是trhat是我的第一个方法。

hittest subview

虽然你不想与子视图但有子视图的边缘测试，我认为这将是可能的。

snapping to edge

上面的链接看起来像一个平滑边缘剪裁。扭转逻辑，你应该能够剪辑到边界...

Answer 2

你可以尝试使用一种方法来检查UIImageView的边缘是否在超级视图的框架的一定距离内。

func checkEdge(view: UIImageView) { 

    let left = view.frame.minX 
    let right = view.frame.maxX 
    let bottom = view.frame.maxY 
    let top = view.frame.minY 

    if left <= 10 { 
     // Move view to left side 
    } else if right <= 10 { 
     // Move view to right side 
    } else if bottom <= 10 { 
     // Move view to bottom 
    } else if top <= 10 { 
     // Move view to top 
    } else { 
     // Do nothing 
    } 
} 

让我知道这是否工作和/或你在找什么！