Objective-C protocol uses three steps

The Protocol application calls each other between two controllers or between the Controller and the custom uiview.

Its Applications are similar to interfaces in Java or C. Assume that a calls B and B calls back a, so we can design it as follows:

First, define a protocal:

@ Protocol ptlchart

@ Optional
-(Void) callback :( ID) ARG;

@ Required
-(Void) loaddata;
@ End

 

 

Step 2: Define protocal delegate in B:

Code

// B. H
@ Interface B: uiview {
ID <ptlchart> _ delegate;
}

@ Property (nonatomic, retain) ID <ptlchart> delegate;

@ End

// B. M:
# Import "B. H"

@ Implementation B

@ Synthesize delegate = _ delegate;

-(Void) dealloc {
[_ Delegate release];
}
@ End

 

 

Step 3: Pass the delegate when calling B in:

Code

// A. H:
@ Interface A: uiviewcontroller <ptlchart>

@ End
// A. M:
# Import "A. H"

@ Implementation

-(Void) loaddata {
A * A = [[A alloc] init];
[A setdelegate: Self]; // <--------- here
[Self. View addsubview: A];
[A release];
}

-(Void) callback :( ID) Arg {
Int I = (INT) ARG;
Nslog (@ "Callback = % d", I );
}
@ End