IOS Accessing one view from another view

Question

Basically I have a view controller having two subviews. I want these views to be connected. A touch event should trigger an event from another view and vice versa. I have thought about two solutions.

1-) Accessing views through their view controllers

2-) Each view has a pointer to another view

I am a newbie on IOS and as far I read from other problems it is mentioned that accessing view controller from a view is not suggested. So, what do you guys suggest me to do?

Edit:

I didn't make much progress on coding but my first view is:

@interface PaintView : UIView
-(id)initWithFrame:(CGRect)frame andController:(ViewController*)ctrl;

and i will control the touch event and access my viewcontroller:

-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
     //[self.controller somethingThatAccessToOtherView]
}

and second view will be very similar to that one.

I have added some code to show my views. – mayy00 Jan 07 '13 at 06:16 — mayy00, Jan 07 '13 at 06:16

Aatish Molasi · Accepted Answer · 2020-06-13T06:38:12.127

1

Why dont you use the delegate pattern!
For the two views communicate with each other .. Its essentially similar to " Each view has a pointer to another view" but in a much more flexible manner

here is a so thread on it and

edited Jun 13 '20 at 06:38

answered Jan 07 '13 at 06:24

Aatish Molasi

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Thanks, I am now checking it – mayy00 Jan 07 '13 at 06:35

score 1 · Answer 2 · answered Jan 07 '13 at 06:28

If you want the simplest, dirtiest, and non recommended way of proceeding. Tag your two views with some sort of unique tag (use say, -20 and -21, or something. So in the view controller where you create the views you do the following.

[v1 setTag:-20];
[v2 setTag:-21];

Then you can do from in say, v2, the following.

[self.superview viewWithTag:-20];

to get a reference to v1. However, this assumes the same superview, and is not a nice way of doing things unless you are sure that the view heirachy will not change (I'm talking, it's a widget you made that no one else is going to touch and you've documented it well anyway).

A better way would be to use a delegate pattern. The ViewController is the delegate of each of the subviews. On touch, the subviews call some method like

[delegate iwastouched:self];

and the delegate has a method like

-(void) iwastouched:(UIView *) someview {
     if(someview == v1){
         //view 1 was touched, do something to view two
     }
     if(someview == v2){
         //view 2 was touched, do something to view one
     } 
}

Another bad way of doing it would be to use notifications. Hell, there are about as many ways to do this as you could like. Some are just not as nice.

Thanks for the detailed answer! First and the last ways seemed not good, I will go with the delegate. — mayy00, Jan 07 '13 at 06:37

score 0 · Answer 3 · answered Jan 07 '13 at 06:22

0

Instead of doing this, in the subclass of UIViewController, you should have two members. These member will represent each of the subview.

Now, inside the subclass of UIViewController, add the methods of touch which are of your interest. Inside this methods, identify the view on which any touch event is generated.

Depending on it, pass the event to other view.

You should not have UIViewController as a iVar of your UIView subclass.

answered Jan 07 '13 at 06:22

Apurv

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But in this case, I have to control which view has the touch event inside it. Isn't it an extra burden for the developer calculate it? – mayy00 Jan 07 '13 at 06:27
But views can be rotated and developer can have more than 2 views. It makes the situation tougher – mayy00 Jan 07 '13 at 06:40

IOS Accessing one view from another view

3 Answers3