iOS has to reverse the value by proxy

Application scenario: Sometimes from interface a jump to interface B, interface B in return to the need to pass the results of processing to a.

Implementation ideas: 1, define a responsible for the value of the covariance, interface A has the semantic attributes, and implement the method of the covariance

2, Interface B also has this semantic attribute (the proxy requires both have a reference to the same object), then gets the reference pointer of interface A when it returns, and specifies that the calling target of the "B" is a, calling the method of value in the covariance.

Specific code:

A's header file:

#import <UIKit/UIKit.h>

@protocol passvaluedelegate <nsobject>

-(void) SetValue: (nsstring *) param;

@end

@interface Viewcontroller: Uiviewcontroller

@propertyID<passvaluedelegate> passvaluedelegate;

@end

Implementation file for a:

#import "ViewController.h"

#import "ViewController2.h"

@interfaceviewcontroller ()

{

}

@end

@implementation Viewcontroller

-(void) viewdidload

{

[superviewdidload];

Additional setup after loading the view, typically from a nib.

UIButton *btn =[UIButtonbuttonwithtype:uibuttontyperoundedrect];

Btn. frame=CGRectMake(+,+, +);

    [btn settitle: @ "btn" Forstate: uicontrolstatenormal";

    [btn addtarget: self Action: @selector (BTN) forcontrolevents: uicontroleventtouchupinside";

[self. Viewaddsubview: btn];

self. View. BackgroundColor=[uicolorredcolor];

}

-(void) SetValue: (NSString *) param{

NSLog (@ "Pass value is:%@", param);

}

-(void) btn

{

[self. Navigationcontroller pushviewcontroller:[[viewcontroller2 Alloc]init] Animated:YES];

}

-(void) didreceivememorywarning

{

[Super didreceivememorywarning];

//Dispose of any resources, can be recreated.

}

@end

B's header file:

#import <UIKit/UIKit.h>

@interface ViewController2:Uiviewcontroller

@end

Implementation file of B:

#import "ViewController2.h"

#import "ViewController.h"

@interfaceViewController2 ()

@property ID<passvaluedelegate> passvaluedelegate;

@end

@implementation ViewController2

-(void) viewdidload

{

[superviewdidload];

UIButton *btn =[UIButtonbuttonwithtype:uibuttontyperoundedrect];

Btn. frame=CGRectMake(+,+, +);

[btn settitle:@ "Back"forstate:uicontrolstatenormal];

[btn addTarget:self action:@selector(BTN) forControlEvents:uicontroleventtouchupinside];

[self. Viewaddsubview: btn];

}

-(void) btn

{

//NSLog (@ "%@", Self.navigationcontroller.childviewcontrollers[0]);

    self Passvaluedelegate= self Navigationcontroller Childviewcontrollers[ 0 ];

[self. Navigationcontrollerpoptorootviewcontrolleranimated:YES];

[self. PassvaluedelegatesetValue:@ "123456789"];

}

-(void) didreceivememorywarning

{

[superdidreceivememorywarning];

//Dispose of any resources, can be recreated.

}

@end