Question

I’m looking for a smart way to remove a subview (with removeFromSuperview) when the subview itself (or precisely said one of its components) triggered the removal. As for the source code this would be like

UIView * sub_view = [[[UIView alloc] initWith...

UIButton *button = [UIButton buttonWithType...

[sub_view addSubview:button];

[self.view addSubview:sub_view];

If the button have now something like

[button addTarget:self action:@selector(closeMySubview) forControlEvents:UIControlEventTouchUpInside];

the call to removeFromSuperview inside closeMySubview does not work but results in SIGABRT and unrecognized selector sent to instance … . Well that there is something not more present anymore is not a surprise but what would be the right way?

(Removing the subview if triggered from an another gui component would work of cause but is not the point here.)

Answer 1

The best pattern for this type of action is the “delegate” pattern.

You can subclass anything and add this property:

@property (assign) id delegate;

for the instance variable:

id delegate;

Also, define a protocol like this:

@protocol MySubViewDelegate

    -(void)myViewDidFinish:(UIView *)view;

So in your view controller, you can instantiate the subview, tell it your its delegate, and add it to the view. Then, an action on the subview calls the method:

[delegate myViewDidFinish:self];

The viewcontroller then can say something like:

[view removeFromSuperView];