iOS - 代理的封装用法

把代理写进一个类里面，这个类.h不声明，所以.m也就不用实现。既然不实现，那留着它也就无意义了，所以，我把它删了。

流程就是这样： viewController-->FirstViewController-->SecondViewController,其中返回的过程中，Second 会传值给 First, 而 First 则会给 ViewController 传值。依次看代码就好:

// ZJJPassTheNumberDelegate.h

// ProjectZJJ

// Created by ZJJ on 2017/8/4.

#import <Foundation/Foundation.h>

@protocol ZJJPassTheNumberDelegate <NSObject>

- (void)passTheNumberWithNum:(int)num;

@end

// ViewController.h

// ProjectZJJ

// Created by ZJJ on 2017/8/3.

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@end

// Created by ZJJ on 2017/8/3.

#import "ViewController.h"

#import "FirstViewController.h"

@interface ViewController () <ZJJPassTheNumberDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

self.view.backgroundColor = [UIColor cyanColor];

}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

FirstViewController *first = [[FirstViewController alloc] init];

first.delegate = self;

[self presentViewController:first animated:YES completion:nil];

}

- (void)passTheNumberWithNum:(int)num {

NSLog(@"第一个类传过来的值为:%d",num);

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

// FirstViewController.h

// ProjectZJJ

// Created by ZJJ on 2017/8/4.

#import <UIKit/UIKit.h>

#import "ZJJPassTheNumberDelegate.h"

@interface FirstViewController : UIViewController

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

@end

// FirstViewController.m

// ProjectZJJ

// Created by ZJJ on 2017/8/4.

#import "FirstViewController.h"

#import "SecondViewController.h"

@interface FirstViewController () <ZJJPassTheNumberDelegate>

@end

@implementation FirstViewController

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view.

self.view.backgroundColor = [UIColor whiteColor];

UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];

button.frame = CGRectMake(100, 100, 100, 50);

button.backgroundColor = [UIColor cyanColor];

[button setTitle:@"返回" forState:UIControlStateNormal];

[button setTitleColor:[UIColor yellowColor] forState:UIControlStateNormal];

[button addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:button];

}

- (void)back {

if ([self.delegate respondsToSelector:@selector(passTheNumberWithNum:)]) {

[self.delegate passTheNumberWithNum:10];

}

[self dismissViewControllerAnimated:YES completion:nil];

}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

SecondViewController *second = [[SecondViewController alloc] init];

second.protocal = self;

[self presentViewController:second animated:YES completion:nil];

}

- (void)passTheNumberWithNum:(int)num {

NSLog(@"第二个类传过来的值为:%d",num);

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

// SecondViewController.h

// ProjectZJJ

// Created by ZJJ on 2017/8/4.

#import <UIKit/UIKit.h>

#import "ZJJPassTheNumberDelegate.h"

@interface SecondViewController : UIViewController

@property (nonatomic, assign) id <ZJJPassTheNumberDelegate> protocal;

@end

// SecondViewController.m

// ProjectZJJ

// Created by ZJJ on 2017/8/4.

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view.

self.view.backgroundColor = [UIColor lightGrayColor];

}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

if ([self.protocal respondsToSelector:@selector(passTheNumberWithNum:)]) {

[self.protocal passTheNumberWithNum:100];

}

[self dismissViewControllerAnimated:YES completion:nil];

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

iOS - 代理的封装用法

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