iOS开发 -- delegate 设计模式

当一个类的某些功能需要被别⼈来实现，但是既不明确是些什么 功能，⼜不明确谁来实现这些功能的时候，委托模式就可以派上⽤场。

delegate 设计模式目的是为了降低类之间的耦合性

delegate 是用来解耦的，它不再简简单单让目标去执行一个动作

使用场景

控件有一些列时间点，控制器可以实现这个代理方法，以便在适当 的时机做适当的事

.h文件

@class TouchView;

设置代理

@protocol TouchViewDelegate <NSObject>

当视图被触摸的时候 触发的方法

-(void)touchViewDidTouchBegan:(TouchView *)touchView;

@end

设置代理属性 代理用assign

@interface TouchView : UIView

@property(nonatomic,assign)id<TouchViewDelegate> delegate;

@end

在.m文件

让代理执行协议中的方法

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
//让代理执行协议中的方法
[_delegate touchViewDidTouchBegan:self];
}

在控制器中遵守协议

#import "RootViewController.h"
#import "TouchView.h"

@interface RootViewController ()<TouchViewDelegate>

@end

@implementation RootViewController

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
TouchView *touchView  = [[TouchView alloc]initWithFrame:CGRectMake(20, 100, 275, 100)];
touchView.backgroundColor = [UIColor redColor];
[self.view addSubview:touchView];
[touchView release];

TouchView *touchView2  = [[TouchView alloc]initWithFrame:CGRectMake(20, 250, 275, 100)];
touchView2.backgroundColor = [UIColor cyanColor];
[self.view addSubview:touchView2];
[touchView2 release];

TouchView *touchView3  = [[TouchView alloc]initWithFrame:CGRectMake(20, 400, 275, 100)];
touchView3.backgroundColor = [UIColor blueColor];
[self.view addSubview:touchView3];
[touchView3 release];

//设置代理
touchView.delegate = self;
touchView2.delegate = self;
touchView3.delegate = self;

//设置tag
touchView.tag = 100;
touchView2.tag = 101;
touchView3.tag = 102;
}
//实现方法
-(void)touchViewDidTouchBegan:(TouchView *)touchView
{
if (touchView.tag == 100) {
NSLog(@"Color");
[self changeColor:touchView];
}else if (touchView.tag == 101)
{
NSLog(@"Posist");
[self changePosist:touchView];
}else if (touchView.tag ==102)
{
NSLog(@"Size");
[self changeSize:touchView];
}

}
-(void)changeColor:(TouchView *)touchView
{
touchView.backgroundColor = [UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1.0];
}

-(void)changePosist:(TouchView *)touchView
{
touchView.center= CGPointMake(arc4random()%(325 - 100 +1)+100, arc4random()%(400-100+1)+100);
}

-(void)changeSize:(TouchView *)touchView
{
touchView.bounds = CGRectMake(0, 0, arc4random()%(275 - 100 +1)+100, arc4random()%(200-100+1)+100);
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end