iOS中UIView实现不同方向的导角

所属分类：软件编程 / IOS 阅读数： 657

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前言

开发中总因为一些比较蛋疼的导角问题而困扰着我们,尤其是我们要给一个UIView导角成左上、左下。。。

这种需求很值得用代码实现一下, 今天突然在AppCode找到了一篇好文章.于是有了下文

通常导角

self.view.cornerRadius = 20.0
self.view.clipToBounds = true

这两行代码是全方向导角

如果像要搞成不同方向的话可以用iOS11 新的API和 iOS11以前的CAShapeLayer画贝赛尔曲线来解决

首先我们要创建一个UIView

class ViewController: UIViewController {
 var cardView: UIView!
 override func viewDidLoad() {
  super.viewDidLoad()
  cardView = UIView()
  view.addSubview(cardView)
cardView.translatesAutoresizingMaskIntoConstraints = false
  //把View居中
  cardView.widthAnchor.constraint(equalToConstant: 200).isActive = true
  cardView.heightAnchor.constraint(equalToConstant: 200).isActive = true
  cardView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
  cardView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
  cardView.backgroundColor = UIColor(red: 1.0, green: 0.784, blue: 0.2, alpha: 1)  
 }
}

iOS11 以后苹果提供了一个UIView的属性叫maskedCorners用于CALayer的动画相关.

public struct CACornerMask : OptionSet {
 public init(rawValue: UInt)
 
 public static var layerMinXMinYCorner: CACornerMask { get }
 public static var layerMaxXMinYCorner: CACornerMask { get }
 public static var layerMinXMaxYCorner: CACornerMask { get }
 public static var layerMaxXMaxYCorner: CACornerMask { get }
}

下面我说一下

layerMinXMinYCorner 底部右侧的圆角 -> 右下角
layerMaxXMinYCorner 顶部右侧的圆角 -> 右上角
layerMinXMaxYCorner 底部左侧的圆角 -> 左下角
layerMinXMinYCorner 顶部左侧的圆角 -> 左上角

一般我们都为UIView写个 extension

extension UIView {
 func roundCorners(cornerRadius: Double) {
  self.layer.cornerRadius = CGFloat(cornerRadius)
  self.clipsToBounds = true
  
  if #available(iOS 11.0, *) {
   self.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
  } else {
   let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: cornerRadius, height: cornerRadius))
   let maskLayer = CAShapeLayer()
   maskLayer.frame = self.bounds
   maskLayer.path = path.cgPath
   self.layer.mask = maskLayer
  }
  
 }
}

这里区分了iOS11之前和之后的两种搞法.

之前的话我们都是用一个贝塞尔曲线画path.然后创建CAShapeLayer 给self.layer.mask做一种透明的遮罩来解决不同方向导角问题.

添加动画效果的导角

我们在原ViewDidLoad()方法里面加个手势.

并写好触发的事件, 完整的代码如下

import UIKit
class ViewController: UIViewController {
 var cardView: UIView!
 override func viewDidLoad() {
  super.viewDidLoad()
  cardView = UIView()
  view.addSubview(cardView)cardView.translatesAutoresizingMaskIntoConstraints = false
  cardView.widthAnchor.constraint(equalToConstant: 200).isActive = true
  cardView.heightAnchor.constraint(equalToConstant: 200).isActive = true
  cardView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
  cardView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
  cardView.backgroundColor = UIColor(red: 1.0, green: 0.784, blue: 0.2, alpha: 1)
  let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(animateCornerChange(recognizer:)))
  cardView.addGestureRecognizer(tapRecognizer)
 }

 @objc func animateCornerChange(recognizer: UITapGestureRecognizer) {
  let targetRadius: Double = (cardView.layer.cornerRadius == 0.0) ? 100.0:0.0
  
  if #available(iOS 10.0, *) {
   UIViewPropertyAnimator(duration: 0.4, curve: .easeInOut) {
    self.cardView.roundCorners(cornerRadius: targetRadius)
    }.startAnimation()
  } else {
   UIView.animate(withDuration: 1.0, delay: 0.0, options: .curveEaseInOut, animations: {
    
   }, completion: nil)
  }
 }
}
extension UIView {
 func roundCorners(cornerRadius: Double) {
  self.layer.cornerRadius = CGFloat(cornerRadius)
  self.clipsToBounds = true
  
  if #available(iOS 11.0, *) {
   self.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
  } else {
   let path = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: CGSize(width: cornerRadius, height: cornerRadius))
   let maskLayer = CAShapeLayer()
   maskLayer.frame = self.bounds
   maskLayer.path = path.cgPath
   self.layer.mask = maskLayer
  }
 }
}

这里主要强调一下动画的新API

iOS10之后U增加一个新的动画效果API

UIViewPropertyAnimator(duration: 0.4, curve: .easeInOut) {
//这里写相关View的操作代码 。。。eg:下面代码
    self.cardView.roundCorners(cornerRadius: targetRadius)
    }.startAnimation()

iOS之前可以通过古老的API来实现

UIView.animate(withDuration: 1.0, delay: 0.0, options: .curveEaseInOut, animations: {
//这里写相关View的操作代码 。。。eg:下面代码
    self.cardView.roundCorners(cornerRadius: targetRadius)
   }, completion: nil)

最终的效果