ios开发-- 开发细节（代理传值）

代理委托
逻辑
定义两个控制器 classA 、classB

classA 推出 classB classB返回classA

classA 实现代理的方法 ，delegate = self；
classB定义delegate 并在返回的时候调用方法传值

classA.h

#import <UIKit/UIKit.h>

@interface classA : UIViewController


@end

classB.m

#import "classA.h"
#import "clasB.h"
@interface classA ()<classBDelegate>

@end

@implementation classA

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

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (IBAction)btn:(id)sender {
    clasB *vc = [[clasB alloc] init];
    vc.delegate = self;
    [self presentViewController:vc animated:YES completion:nil];

}
- (void)print:(NSString *)str {
    NSLog(@"%@",str);
}

@end

classB.h

#import <UIKit/UIKit.h>
@protocol classBDelegate <NSObject>

- (void)print:(NSString *)str;

@end
@interface clasB : UIViewController
@property(nonatomic,assign)id<classBDelegate>delegate;

@end

classB.m

#import "clasB.h"

@interface clasB ()

@end

@implementation clasB

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];
    btn.frame = CGRectMake(100, 100, 60, 30);
    btn.backgroundColor  = [UIColor lightGrayColor];
    [btn setTitle:@"12" forState:UIControlStateNormal];
    [self.view addSubview:btn];
    [btn addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (void)click:(id)sender {
    if (_delegate) {
        [_delegate print:@"vcvc"];
    }
    [self dismissViewControllerAnimated:YES completion:nil];
}

@end