UI delegate

代理模式：

一个委托人

一份协议

一个代理者

1、

#import "AppDelegate.h"

//2、设置协议

@interface AppDelegate () <UITextFieldDelegate>

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

// Override point for customization after application launch.

#pragma mark ======= 1、创建窗口 ========================

self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];

self.window.backgroundColor = [UIColor whiteColor];

[self.window makeKeyAndVisible];

#pragma mark ======== 2、创建一个文本编辑框 ================

UITextField *textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 100, 200, 30)];

textField.placeholder = @"编辑";

[self.window addSubview:textField];

#pragma mark ========= 设置代理 =========================

//1、将当前类对象设置为输入框的代理

textField.delegate = self;

//2、遵从协议

//3、实现协议方法

//第一响应者:first responder

return YES;

}

//3、实现协议方法===参数:设置代理的人

-(BOOL)textFieldShouldReturn:(UITextField *)textField

{

//释放第一响应者

[textField resignFirstResponder];

return YES;

}

2、

#import <UIKit/UIKit.h>

@interface MyAppDelegate : UIResponder <UIApplicationDelegate>

@property(nonatomic,strong) UIWindow *window;

@end

3、

#import "MyAppDelegate.h"

@implementation MyAppDelegate

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{

self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];

self.window.backgroundColor = [UIColor whiteColor];

[self.window makeKeyAndVisible];

UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(50, 80, 200, 50)];

label.text = @"自己写的AppDelegate";

label.textColor = [UIColor redColor];

[self.window addSubview:label];

return YES;

}

@end