Question

So this is the code i have:

ViewA.h:

#import "ViewB.h"
#import "ViewC.h"

@interface ViewA : UIViewController {

    ViewB *viewB;
    ViewC *viewC;

}

@property(nonatomic,retain) ViewB *viewB;

@end

ViewA.m:

@synthesize viewB;

-(void)viewDidLoad {
viewB = [[ViewB alloc] initWithFrame:CGRectMake(0, 0, 320, 328)];
    [self.view addSubview:viewB];

   viewC = [[ViewC alloc] initWithFrame:CGRectMake(0, 332, 320, 84)];
    [self.view addSubview:viewC];

    }

ViewB.h:

-(void)methodToPass;

ViewB.m:

-(void)methodToPass {

NSLog(@"Passed.");
}

ViewC.h:

#import "ViewB.h"

@interface ViewC : UIScrollView {

ViewB *viewB;

}

-(void)methodWhichDoesGetPassed;

ViewC.m:

#import "ViewA.h"

@implementation ViewC

ViewA *viewA;

-(void)methodWhichDoesGetPassed {
NSLog(@"Test here");
[viewA.viewB methodToPass];

}

So the key bit of that is that i tried to pass the method to viewB, from viewC, through viewA in that last part. When i run the app, i get the “Test here” but not the “Passed”, so it doesn’t pass this through.

Any ideas how to fix this?

Answer 1

Since viewC is a subview of viewA, you should send messages to the superview.

change it to

ViewA *view = (ViewA *)self.superview;

[view.viewB methodToPass];

EDIT

You can even check if the superview is an instance of ViewA before casting.

if ( [self.superview isMemberOfClass:[ViewA class]] ) {
    ViewA *view = (ViewA *)self.superview;
    [view.viewB methodToPass];
}

EDIT2

Rather than having to message up to viewA and down to viewB again, wouldn’t it be better to pass viewB to viewC on instantiation. Suggesting some changes based on that.

ViewA.m:

@synthesize viewB;

-(void)viewDidLoad {
    viewB = [[ViewB alloc] initWithFrame:CGRectMake(0, 0, 320, 328)];
    [self.view addSubview:viewB];

    viewC = [[ViewC alloc] initWithFrame:CGRectMake(0, 332, 320, 84)];
    viewC.viewB = viewB;
    [self.view addSubview:viewC];

}

ViewC.h:

#import "ViewB.h"

@interface ViewC : UIScrollView {
    ViewB *viewB;
}
@property (nonatomic, retain) ViewB *viewB;

-(void)methodWhichDoesGetPassed;
...
@end

ViewC.m:

@implementation ViewC

@synthesize viewB;

-(void)methodWhichDoesGetPassed {
    NSLog(@"Test here");
    [viewB methodToPass];

}

Original Answer