如何不断更新UIView中的绘图

Question

我不断从源读取数据（CGFloat数组），并且我想从该数据源上的UIView上绘制一条线。

我知道我需要使用UIBezierPath来创建该行。我最初可以这样做，但我不知道如何继续更新UIView上的图形[就像一系列path.move（..）]。

有谁知道如何实现这个？

TIA

Answer 1

子类的UIView并重写draw RECT方法：

import UIKit 

class MyLineView: UIView { 
    // Edit:add the data to draw 
    public var lineData : Array<Float>? 

    override func draw(_ rect: CGRect) { 
     // Read the values and draw the lines 
     // using your bezier functions 

     // Edit: just to test - you can see the new data 
     if let data = lineData { 
      print("Redrawing \(data.count) elements") 
     } 
    } 
} 

在视图控制器创建Timer类型的属性，并开始它在适当的点与期望的帧速率会：

import UIKit 

class ViewController: UIViewController { 

    var animationTimer : Timer? 
    var myLineView : MyLineView? 
    **// Edit: add an array of data** 
    var myData : Array<Float>? 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     self.myLineView = MyLineView(frame: self.view.bounds) 
     self.view.addSubview(myLineView!) 
     // Edit: init data 
     self.myData = Array() 
    } 

    override func viewDidAppear(_ animated: Bool) { 
     super.viewDidAppear(animated) 

     // Update the view at roughly 10Hz 
     animationTimer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true, block: { (timer) in 
      //Edit: example update of the data before redrawing 
      self.myData?.append(Float(1)) 
      self.myLineView!.lineData = self.myData! 

      self.myLineView!.setNeedsDisplay() 
     }) 
    } 

    override func viewDidDisappear(_ animated: Bool) { 
     super.viewDidDisappear(animated) 

     // Stop updating 
     animationTimer!.invalidate() 
     animationTimer = nil 
    } 
} 

这将以近似10Hz的频率调用子类的drawRect。