iOS 实现加载转圈效果

1、思路：

新建一个view，添加shape，给予一个动画实现。

 

2、效果图：

效果1:

 

效果2:

 

 

gif有点卡，代码运行不会这样。

 

3、源码（整个类放进来的）

效果1源码：

//
//  YJDownloadingCircle.swift
//  k12_sl_iOS
//
//  Created by liyajun on 2017/7/13.
//
//

import UIKit

class YJDownloadingCircle: UIView {

    var loadingLayer:CAShapeLayer! = nil
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        initViews()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        initViews()
        
    }
    
    override func awakeFromNib() {
        initViews()
    }
    
    func initViews() {
        backgroundColor = UIColor.white
    }
    
    
    func drawHalfCircle() {
        loadingLayer = self.drawCircle()
        
        loadingLayer.strokeStart = 0.0
        loadingLayer.strokeEnd = 0.75
        
        let basicAni = CABasicAnimation(keyPath: "transform.rotation.z")
        basicAni.fromValue = 0.0
        basicAni.toValue = M_PI*2
        basicAni.duration = 0.5
        basicAni.repeatCount = MAXFLOAT
        basicAni.autoreverses = false
        basicAni.fillMode = kCAFillModeForwards
        self.layer.add(basicAni, forKey: nil)
        
    }
    
    private func drawCircle() -> CAShapeLayer {
        
        let circleLayer = CAShapeLayer()
        let rect = CGRect(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height)
        circleLayer.frame = rect
        circleLayer.position = CGPoint(x: self.frame.size.width/2, y: self.frame.size.height/2)
        circleLayer.fillColor = UIColor.clear.cgColor
        circleLayer.lineWidth = 1
        circleLayer.strokeColor = UIColor.colorWithHex(hex: "FF3B30").cgColor
        let bezier = UIBezierPath(ovalIn: rect)
        circleLayer.path = bezier.cgPath
        self.layer.addSublayer(circleLayer)
        
        return circleLayer
        
    }
}

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