讓用戶繪製矩形來選擇區域

Question

我是Swift中的新手，我試圖讓用戶繪製一個矩形（觸摸並拖動）來選擇圖像的一個區域，就像剪切時一樣，但我不'不想裁剪我只想知道用戶創建的CGRect。

到目前爲止，我有一個內部的UIImage和它的ViewController .xib。我想要在圖像上面繪製，但是我發現的關於繪圖的每個教程都是關於UIView的子類，重寫drawRect並將其作爲xib類。

Answer 1

我想通了。我剛剛創建了一個uiview，並根據觸摸事件更改其框架

let overlay = UIView() 
var lastPoint = CGPointZero 

override func viewDidLoad() { 
    super.viewDidLoad() 

    // Do any additional setup after loading the view. 
    overlay.layer.borderColor = UIColor.blackColor().CGColor 
    overlay.backgroundColor = UIColor.clearColor().colorWithAlphaComponent(0.5) 
    overlay.hidden = true 
    self.view.addSubview(overlay) 

} 

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) { 

    //Save original tap Point 
    if let touch = touches.first { 
     lastPoint = touch.locationInView(self.view) 
    } 
} 

override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) { 
    //Get the current known point and redraw 
    if let touch = touches.first { 
     let currentPoint = touch.locationInView(view) 
     reDrawSelectionArea(lastPoint, toPoint: currentPoint) 
    } 
} 

func reDrawSelectionArea(fromPoint: CGPoint, toPoint: CGPoint) { 
    overlay.hidden = false 

     //Calculate rect from the original point and last known point 
     let rect = CGRectMake(min(fromPoint.x, toPoint.x), 
     min(fromPoint.y, toPoint.y), 
     fabs(fromPoint.x - toPoint.x), 
     fabs(fromPoint.y - toPoint.y)); 

    overlay.frame = rect 
} 

override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) { 
    overlay.hidden = true 

    //User has lift his finger, use the rect 
    applyFilterToSelectedArea(overlay.frame) 

    overlay.frame = CGRectZero //reset overlay for next tap 
}