objective c - Delegation and childVIewController -

this question regarding delegation, trying pass data child view controller linked container view has picker view. asked related question before , kind enough reply following code:

"i'm going explain example how delegation works.

edit childviewcontroller.h this:"

@protocol childviewcontrollerdelegate;   @interface childviewcontroller : uiviewcontroller  @property (weak)id <childviewcontrollerdelegate> delegate;  @end  @protocol childviewcontrollerdelegate <nsobject >   - (void) passvalue:(uicolor *) thevalue;  @end 

"on childviewcontroller.m when want pass parentviewcontroller , this:"

 - (void) mymethod  {    [delegate passvalue:[uicolor redcolor]]; // pass value here  } 

on parentviewcontroller.h

#import "childviewcontroller.h"  @interface parentviewcontroller : uiviewcontroller <childviewcontrollerdelegate >  // adopt protocol { } 

on parentviewcontroller.m:

- (void) passvalue:(uicolor *) thevalue    {       //here receive color passed childviewcontroller    } 

now careful. work if set delegate. when declare childviewcontroller inside parentviewcontroller class, this:

childviewcontroller * controller = [[childviewcontroller alloc]initwithinibname:@"childviewcontroller"];  controller.delegate = self; //without line code won't work!" 

anyway, helped me quite bit , 1 of helpful pieces of advice have got yet. unfortunately, 1 of lines in code returns error , making delegate nil. one:

 childviewcontroller * controller = [[childviewcontroller alloc]initwithinibname:@"childviewcontroller"]; 

the error is: "no visible @interface 'childviewcontroller' declares selector 'initwithnibname:'

as following instructions on trying learn, bit lost. begin with, when try type it, proposed method takes argument: [[childviewcontroller alloc]initwithnibname:<#(nullable nsstring *)#> bundle:<#(nullable nsbundle *)#>];

i have done nslog [self.delegate description] , it's come null. can help? thanks

it sounds delegation advice good, left off parameter building view controller via storyboard.

childviewcontroller *controller = [[childviewcontroller alloc]         initwithnibname:@"childviewcontroller"                  bundle:[nsbundle mainbundle]]; 

...will work, if there's interface builder file in project called "childviewcontroller".