can't map single object (UIView, UIGesture) with two other objects (UIView)?

Question

I have some confusion. Not really a bug or issue I am facing. I want to know something and I am not sure this is right place for this kind of question but here is my question:

In reference to my Question Here I was trying to map single gesture on two views.

Now I am keen to know that why this is not working? I went on basics that in case I have any NSObject subclass lets say if NSString and I add this in an NSMutableArray as follows:

 NSString *strTest = @"Test String";
 [aryTest1 addObject:strTest];
 [aryTest2 addObject:strTest];

String gets added in both of array. Now what I am doing is I created a label, set tag for the label and added that in two views as follows:

 UILabel *lblTemp = [[UILabel alloc] initWithFrame:CGRectMake(10, 10, 100, 20)];
[lblTemp setTag:1];
[lblTemp setText:@"Label"];
[vw1 addSubview:lblTemp];
[vw2 addSubview:lblTemp];

Now every view has an array of subview. When we try to add an object in that view's subview why this is not being added in both of view? I am getting a result that my second view is showing the label but first view is not having the label.

If I comment the last line of my code and don't add label in vw2 the label will be added in vw1. Than I tried a different thing.

UILabel *lblTemp = [[UILabel alloc] initWithFrame:CGRectMake(10, 10, 100, 20)];
[lblTemp setTag:1];
NSMutableArray ary1 = [[NSMutableArray alloc] init];
NSMutableArray ary2 = [[NSMutableArray alloc] init];
[ary1 addObject:lblTemp];
[ary2 addObject:lblTemp];

both array has count 1. Thats mean that I have label added in my array. after that I tried to add array's object in view than even ame problem. Label is only being added in second view:

 [vw1 addSubview:[ary1 objectAtIndex:0]];
 [vw2 addSubview:[ary2 objectAtIndex:0]];

When I printed retainCount of Label after initialize, adding in array1 and array2 everytime the retaincount was 1. So I think the array are not keeping the reference of same object. Its a new object copied in array. Than why label is not being added in same view?

What is actual internal process for a object to add on any view's subview. As of I know subview is an Array type than what happening? Can anyone explain me?

Thanks in Advance

that I know.. I just called it to know does anything happens in memory if I add any object in array.. and the answer was NO. — Kapil Choubisa, May 07 '12 at 06:40

score 0 · Accepted Answer · answered May 05 '12 at 08:41

The difference is that addSubview automatically removes a view from it's super view before adding it to the new view (See the class reference: http://developer.apple.com/library/ios/ipad/#documentation/uikit/reference/uiview_class/uiview/uiview.html) while an array will happily accept an object even if it is in another array.

You can create a copy of the label and place it in the other view though if this is what you need to do.

can't map single object (UIView, UIGesture) with two other objects (UIView)?

1 Answers1