IOS Proxy reverse-pass value

In the previous blog iOS Agent protocol, focusing on the concept of principal-agent protocol, this article will focus on their application in the development.

If we have a demand as follows: interface A has a button, a label. From interface a jump to interface B, enter the string in the input box of interface B and display it on the label of interface A. This is a typical example of a reverse value. The core of this example is: "Enter the string in the input box of interface B and display it on the label on interface A." That is: "Interface B Delegate interface a display string, page A is the agent of interface B." The delegate direction agent reverses the value.

So how do we use the proxy design pattern to implement this requirement?

In the program:

1. The tasks to be commissioned are:

1.1 Defining protocols and methods

1.2 Declaring a delegate variable

1.3 Setting up Proxies

1.4 Calling a delegate method from a delegate variable

2. The work that the agent needs to do is:

2.1 Following the agreement

2.2 Implementing a Delegate method

In the BViewController.h:

Define protocols and methods @protocol deliverdetegate <nsobject>-(void) SetValue: (NSString *) string; @end @interface bviewcontroller:uiviewcontroller//declares the delegate variable @property (weak,nonatomic) id<deliverdetegate>b_delegate; @end

In the BVIEWCONTROLLER.M:

@interface Bviewcontroller () <UITextFieldDelegate> @property (Strong, nonatomic) iboutlet Uitextfield * Delivertext; @end

-(Ibaction) Deliveraction: (ID) Sender {/        /The delegate method//input through the delegate variable    displays the input string, not entered displays "not filled"    if (![ _delivertext.text isequaltostring:@ ""]) {        NSLog (@ "b to send data%@", _delivertext.text);        Determine if the method in the proxy is implemented, and avoid a program that is not implemented by the agent crashes        if (self. B_delegate respondstoselector: @selector (setValue:)])        {            [self. B_delegate Setvalue:_delivertext.text];        }    }    else    {        NSLog (@ "B sends data%@", @ "not filled in");        Determine if the method in the proxy is implemented, and avoid a program that is not implemented by the agent crashes        if (self. B_delegate respondstoselector: @selector (setValue:)])        {            [self. B_delegate setvalue:@ "not filled"];        }    }        [Self.navigationcontroller Popviewcontrolleranimated:yes];}

In the AVIEWCONTROLLER.M

#import "AViewController.h" #import "BViewController.h" @interface Aviewcontroller () <deliverdetegate>@ Property (Strong, Nonatomic) Iboutlet UILabel *textlabel; @end

-(Ibaction) Receiveaction: (ID) Sender {        //follow protocol    BVIEWCONTROLLER*BVC = [[Bviewcontroller alloc]init];    BVC. B_delegate = self;    [Self.navigationcontroller PUSHVIEWCONTROLLER:BVC animated:yes];}

Implementation of the delegate method, that is, the implementation of the SetValue Method-(void) SetValue: (NSString *) string{    NSLog (@ "A received B data%@", string);    _textlabel.text = string;}

The last of the following:

Output log:

As this article is using Xib, omitted some UI details, attached to the code of this article link: source.

Where to write bad, hope to comment on the guidance. thanked ~

IOS Proxy reverse-pass value