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*
        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: , y: , width: self.frame.size.width, height: self.frame.size.height)
        circleLayer.frame = rect
        circleLayer.position = CGPoint(x: self.frame.size.width/, y: self.frame.size.height/)
        circleLayer.fillColor = UIColor.clear.cgColor
        circleLayer.lineWidth =
        circleLayer.strokeColor = UIColor.colorWithHex(hex: "FF3B30").cgColor
        let bezier = UIBezierPath(ovalIn: rect)
        circleLayer.path = bezier.cgPath
        self.layer.addSublayer(circleLayer)

        return circleLayer

    }
}

使用方法

 //定义属性
 var circle:YJDownloadingCircle! = nil

   override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.white

        circle = YJDownloadingCircle(frame: CGRect(x: 100, y: 100, width: 36, height: 36))
        circle.drawHalfCircle()
        self.view.addSubview(circle)

     }

效果2源码：

//
//  LoginLoadingView.swift
//  k12_sl_iOS
//
//  Created by liyajun on 2018/5/30.
//

import UIKit

class LoginLoadingView: UIView {

    var bgShape:CAShapeLayer! = nil
    var runShape:CAShapeLayer! = nil
    var lblShape:CAShapeLayer! = nil

    let startAngle:CGFloat = ;
    let endAngle:CGFloat = CGFloat(0.67 * M_PI);
    let lineWidth:CGFloat = ;

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

        setup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

    func setup() {
        bgShape = CAShapeLayer()
        let bgPath = CGMutablePath()
        bgPath.addEllipse(in: CGRect(x: , y: , width: self.width, height: self.height))
        bgShape.fillColor = UIColor.clear.cgColor
        bgShape.strokeColor = UIColor.colorWithHex("4CD964").withAlphaComponent(0.5).cgColor
        bgShape.lineWidth = lineWidth
        bgShape.lineJoin = kCALineJoinRound
        bgShape.lineDashPattern = [NSNumber(value: ),NSNumber(value:)]
        bgShape.path = bgPath
        self.layer.addSublayer(bgShape)

        runShape = CAShapeLayer()
        let runPath = UIBezierPath(arcCenter: CGPoint(x: , y: ), radius: self.width/, startAngle: startAngle, endAngle: endAngle, clockwise: false)
        runShape.fillColor = UIColor.clear.cgColor
        runShape.strokeColor = UIColor.colorWithHex("4CD964").cgColor
        runShape.lineWidth = lineWidth
        runShape.lineJoin = kCALineJoinRound
        runShape.path = runPath.cgPath
        runShape.position = CGPoint(x: self.width/, y: self.width/)
        self.layer.addSublayer(runShape)

        let anima = CABasicAnimation(keyPath: "transform.rotation.z")
        anima.fromValue =
        anima.toValue = M_PI*
        anima.repeatCount = MAXFLOAT
        anima.duration = 2.0
        anima.isRemovedOnCompletion = false
        runShape.add(anima, forKey: "rotationAnnimation")

        lblShape = CAShapeLayer()
        let gouPath = UIBezierPath()
        gouPath.move(to: CGPoint(x: self.width/-, y: self.width/-))
        gouPath.addLine(to: CGPoint(x: self.width/, y: self.width/+))
        gouPath.addLine(to: CGPoint(x: self.width/+, y: self.width/-))
        lblShape.fillColor = UIColor.clear.cgColor
        lblShape.strokeColor = UIColor.colorWithHex("4CD964").cgColor
        lblShape.lineWidth = lineWidth
        lblShape.lineJoin = kCALineJoinRound
        lblShape.path = gouPath.cgPath
        self.layer.addSublayer(lblShape)
    }

}

使用时，直接init出来就是了

以上的效果都是只有一个类文件（UIView），使用时直接拷贝即可。

其中，关于转圈的前景色、背景色等参数，我没抽出来，大家如果有这需求，可以改一下。

代码是Swift实现加载转圈效果。

如果是OC，参考代码思路即可。

enjoy～