swift中代理的使用

Posted 2020-08-05

下面以自定义的UITableViewCell的代理为例，记录一下swift中代理的使用

controller中的代码如

 1 //
 2 //  ViewController.swift
 3 //  simpleDemo
 4 //
 5 //  Created by liubo on 16/7/25.
 6 //  Copyright © 2016年 liubo. All rights reserved.
 7 //
 8 
 9 import UIKit
10 
11 class ViewController: UIViewController,
12         UITableViewDataSource,
13         UITableViewDelegate,
14         DelegateCellDelegate{
15     
16     var tableView: UITableView?
17     
18     //MARK: -- lifeCycle
19     override func viewDidLoad() {
20         super.viewDidLoad()
21         
22         self.navigationController?.navigationBar.barTintColor = UIColor.cyanColor()
23         self.view.backgroundColor = UIColor.whiteColor()
24         
25         initTableView()
26     }
27     
28     //MARK: -- UITableViewDataSource
29     func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
30         return 10
31     }
32     
33     func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
34         let cell = tableView.dequeueReusableCellWithIdentifier(NSStringFromClass(DelegateCell), forIndexPath: indexPath) as? DelegateCell
35         cell!.textLabel?.text = "\\(indexPath.row)"
36         cell!.delegate = self
37         return cell!
38     }
39     
40     //MARK: -- DelegateCellDelegate
41     func giveLike(btn: UIButton) {
42         print(123)
43     }
44     
45     //MARK: -- private
46     func initTableView() {
47         let tableView = UITableView(frame: CGRectMake(0,0,self.view.width,self.view.height))
48         tableView.backgroundColor = UIColor.whiteColor()
49         tableView.dataSource = self
50         tableView.delegate = self
51         tableView .registerClass(DelegateCell.classForCoder(), forCellReuseIdentifier: NSStringFromClass(DelegateCell))
52         self.tableView = tableView
53         self.view.addSubview(self.tableView!)
54     }
55 }

controller.swift

 Cell中的代码

 1 //
 2 //  DelegateCell.swift
 3 //  simpleDemo
 4 //
 5 //  Created by liubo on 16/7/26.
 6 //  Copyright © 2016年 liubo. All rights reserved.
 7 //
 8 
 9 import UIKit
10 
11 protocol DelegateCellDelegate :NSObjectProtocol {
12     
13     func giveLike(btn:UIButton)
14 }
15 
16 class DelegateCell: UITableViewCell {
17     var likeButton: UIButton?
18     weak var  delegate: DelegateCellDelegate?
19     
20     override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
21         super.init(style: .Default, reuseIdentifier: reuseIdentifier)
22         initSubViews()
23     }
24     
25     func initSubViews() {
26         let like = UIButton(type: .Custom)
27         like.frame = CGRectMake(UIScreen.mainScreen().bounds.size.width - 40, 10, 30, 30)
28         like.backgroundColor = UIColor.orangeColor()
29         like.setTitle("赞", forState: .Normal)
30         like.addTarget(self, action: Selector("lickClicked:"), forControlEvents: .TouchUpInside)
31         likeButton = like
32         self.addSubview(likeButton!)
33     }
34     
35     func lickClicked(sender: UIButton) {
36        delegate?.giveLike(sender)
37         
38     }
39     
40     required init?(coder aDecoder: NSCoder) {
41         fatalError("init(coder) has not been implemented")
42     }
43 
44 }

自定义Cell中的代码

 

在代码中用到了UIView的extension，值得一提的是在swift中可以直接对一个对象的结构体属性的成员进行直接赋值，这一点在OC中是做不到的

如要给一个view设置y值，在swift中可以这样写

public var x: CGFloat {

        get {

            return self.frame.origin.x 

        }

        set {

            self.frame.origin.x = newValue 

        }

    }

而在OC中则要这样写

- (void) setTop: (CGFloat) newtop {

    CGRect newframe = self.frame;

    newframe.origin.y = newtop;

    self.frame = newframe;

}

extension的代码如下

  1 //
  2 //  UIViewExtension.swift
  3 //  joke
  4 //
  5 //  Created by liubo on 16/7/26.
  6 //  Copyright © 2016年 liubo. All rights reserved.
  7 //
  8 
  9 import Foundation
 10 import UIKit
 11 
 12 extension UIView {
 13     //x--left
 14     public var x: CGFloat {
 15         get {
 16             return self.frame.origin.x
 17         }
 18         set {
 19             self.frame.origin.x = newValue
 20         }
 21     }
 22     //y--top
 23     public var y: CGFloat {
 24         get {
 25             return self.frame.origin.y
 26         }
 27         set {
 28             self.frame.origin.y = newValue
 29         }
 30     }
 31     //width
 32     public var width: CGFloat {
 33         get {
 34             return self.frame.size.width
 35         }
 36         set {
 37             self.frame.size.width = newValue
 38         }
 39     }
 40     //height
 41     public var height: CGFloat {
 42         get {
 43             return self.frame.size.height
 44         }
 45         set {
 46             self.frame.size.height = newValue
 47         }
 48     }
 49     //right
 50     public var right: CGFloat {
 51         get {
 52             return self.frame.origin.x + self.frame.size.width
 53         }
 54         set {
 55             self.frame.origin.x = newValue - self.frame.size.width
 56         }
 57     }
 58     //bottom
 59     public var bottom: CGFloat {
 60         get {
 61             return self.frame.origin.y + self.frame.size.height
 62         }
 63         set {
 64             self.frame.origin.y = newValue - self.frame.size.height
 65         }
 66     }
 67     
 68     //中心x
 69     public var centerX :CGFloat {
 70         get {
 71             return self.center.x
 72         }
 73         set {
 74             self.center.x = newValue
 75         }
 76     }
 77     
 78     //中心y
 79     public var centerY :CGFloat {
 80         get {
 81             return self.center.y
 82         }
 83         set {
 84             self.center.y = newValue
 85         }
 86     }
 87     
 88     public var orign: CGPoint {
 89         get {
 90             return self.frame.origin
 91         }
 92         set {
 93             self.frame.origin = newValue
 94         }
 95     }
 96     
 97     public var size: CGSize {
 98         get {
 99             return self.frame.size
100         }
101         set {
102             self.frame.size = newValue
103         }
104     }
105 }

Extension.swift

 

在打出protocol DelegateCellDelegate  {

    func giveLike(btn:UIButton)

}后，发现不能用weak了修饰，代理我们都知道 arc中需要使用weak来避免循环引用造成内存泄漏，此时要在后面加上 :NSObjectProtocol，这样就能用weak来修饰

 

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