IOS re-talk about proxy transfer value

The example of this post is: There is a and B two interface, to achieve the effect is to let a jump to B, then B has a color parameter, when B jumps to a, the color of the parameter to a, in a to use this color to change the color of their interface. 1th step: In the sender (interface B), the establishment of an agreement (declared in the. h header File)

// 协议名一般以本类的类名开头+Delegate (包含前缀) @protocol ConfigViewControllerDelegate <NSObject>// 声明协议方法，一般以类名开头(不需要前缀)- (void)changeBgColor:(UIColor *)color;

B 是委托 1定义协议， 2声明代理， 3调用协议。

2nd Step: The agent protocol in the. h file in the sender (interface B). Outgoing class--declares the proxy.

@interface ConfigViewController : UIViewController// id即表示谁都可以设置成为我的代理@property (nonatomic,weak) id<ConfigViewControllerDelegate> delegate; // ARC使用weak，MRC使用assign@end

3rd Step: Notify the agent in the method in the sender (interface B) (The most important step）

  //这一步一般是在B跳转到A的方法中实现的，我是在B中创建了一个Button,让这个通知代理在Button中跳转方法中实现。  if ([self.delegate respondsToSelector:@selector(changeBgColor:)]) {     // 加入if语句就是先判断在界面A中是否有changeBgColor这个方法，当有这个方法的时候，才进行代理传值。 //一般会先实例化出一个color的对象，在进行代理传值的时候，是带着这个color一起传递过去的。 [self.delegate changeBgColor:color]; //这里的self是界面B，self.delegate就是界面A了 调用（在第4步和第5步的设置中设置了）}

A 1 Follow protocol 2 to set up proxy 3 to implement protocol incoming class----proxy class4th step: Abide by the protocol in the recipient (interface a).

  @interface ViewController () <ConfigViewControllerDelegate>

5th step: Set yourself as the agent in the recipient (interface a).

  ConfigViewController *testVC = [[ConfigViewController alloc] init];  self;

6th step: Implement the method in the protocol in the recipient (interface a).

  - (void)changeBgColor:(UIColor *)color{  self.view.backgroundColor = color;  }

IOS re-talk about proxy transfer value