IOS代理模式（监听器模式）

背景：自定义一个View，在View中进行了一系列的操作后，需要将结果返回给ViewController中，如何实现呢？需要用到delegate模式。

1. 首先定义一个代理协议类，如代码：

@protocol MyCustomViewDelegate <NSObject>

@required
- (void)returnTheResult:(NSString *)result;

@end

2. 创建自定义View ，由于需要将自定义View中的数据传递到ViewController中，所以自定义View中一定要包含一个代理类。

如：MyCustomView.h

#import "MyCustomViewDelegate.h"

@interface MyCustomView : UIView

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

@property(nonatomic,strong) UIButton *button;

@property(nonatomic,strong) UITextField *textField;

@end

3. 自定义View 的实现类如：

@implementation MyCustomView

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// Drawing code
}
*/

- (instancetype)init{
self = [super init];
if (self) {
self.bounds = CGRectMake(0, 0, ScreenWidth, 100);
self.backgroundColor = [UIColor grayColor];
[self initButtonView];
[self initTextField];
}

return  self;
}

- (void)initTextField{
self.textField = [[UITextField alloc]init];
self.textField.frame = CGRectMake(20, 10, ScreenWidth-40, 40);
self.textField.textAlignment = NSTextAlignmentLeft;
self.textField.secureTextEntry = NO;
self.textField.placeholder = @"输入昵称";
[self.textField setBorderStyle:UITextBorderStyleRoundedRect];
[self addSubview:self.textField];
}

- (void)initButtonView{
self.button = [UIButton buttonWithType:UIButtonTypeCustom];
self.button.frame = CGRectMake(20, 50, ScreenWidth-40, 40);
self.button.backgroundColor = [UIColor redColor];
[self.button setTitle:@"OK" forState:UIControlStateNormal];
[self.button addTarget:self action:@selector(clickButton) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:self.button];
}

- (void)clickButton{
NSLog(@"clickButton");
if (self.delegate != nil) {
[self.delegate returnTheResult:self.textField.text];
}
}
@end

4. ViewController中的用法，需要在ViewController中实现这个代理协议

代码如：

@interface ViewController ()<MyCustomViewDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

MyCustomView *myView = [[MyCustomView alloc]init];
myView.frame = CGRectMake(0, 200, ScreenWidth, 200);
myView.delegate = self;
[self.view addSubview:myView];

}
- (void)returnTheResult:(NSString *)result{
NSLog(@"get --result:%@",result);
}