iOS代理回传

在第二个页面.h文件中:

#import <UIKit/UIKit.h>
//1.声明协议，习惯命名方式为 类型+Delegate
//2.@pro不允许紧贴着#import写,没有代码提示
//一.代理回传第一步，声明协议
@protocol NextViewControllerDelegate <NSObject>
-(void)showText:(NSString *)text;
@end

@interface NextViewController : UIViewController
//二.代理回传第二步，声明 协议类型的属性
@property(nonatomic) id<NextViewControllerDelegate> delegate;
@end

在第二个页面的.m中

#import "NextViewController.h"

@interface NextViewController ()

@end

@implementation NextViewController
- (IBAction)clickReturn:(UITextField *)sender {
//三.代理回传第三步，在适当的位置调用协议方法
    [_delegate showText:sender.text];
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

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

在第一个页面.m文件中:

#import "MyViewController.h"
#import "NextViewController.h"
//四.代理回传第四步，引入协议
@interface MyViewController ()<NextViewControllerDelegate>
@property (weak, nonatomic) IBOutlet UILabel *label;
@end
@implementation MyViewController
- (IBAction)click:(id)sender {
    NextViewController *nextVC = [NextViewController new];
//五.代理回传第五步,设置当前视图控制器为 下一页的 代理
    nextVC.delegate = self;
    [self presentViewController:nextVC animated:YES completion:nil];
}
//六.代理回传第六步，引入协议方法
- (void)showText:(NSString *)text{
    _label.text = text;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor greenColor];
}

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



@end