IOS delegate 自定义代理

意义：两个Controller A(SelectDeviceThroughGatewayViewController) B(ScanViewController)

A调用B后，返回A

A中需要显示B回传的值

在B中：

.h

@class ScanViewController;
@protocol PassValueDelegate <NSObject>
-(void)passValue:(NSString *)value;
@end

@interface ScanViewController : UIViewController
@property (nonatomic,weak) id<PassValueDelegate> delegate;
@end

.m 中需要回传值的地方 

  if ([self.delegate respondsToSelector:@selector(passValue:)]) {
             [self.delegate passValue:[obj stringValue]];
        }

 A.m 

@interface SelectDeviceThroughGatewayViewController ()<PassValueDelegate>

 A在调用B时处理delegate

 ScanViewController *controller = [[ScanViewController alloc]init];
     controller.delegate = self;
     [self presentViewController:controller animated:YES completion:nil];

 A中处理返回的值

-(void)passValue:(NSString *)value{
     NSLog(@"----get backcall value=%@",value);
    self.dayLabel.text = value;
}