Remove all subviews?

Question

When my app gets back to its root view controller, in the viewDidAppear: method I need to remove all subviews.

How can I do this?

Answer 1

Edit: With thanks to cocoafan: This situation is muddled up by the fact that NSView and UIView handle things differently. For NSView (desktop Mac development only), you can simply use the following:

[someNSView setSubviews:[NSArray array]];

For UIView (iOS development only), you can safely use makeObjectsPerformSelector: because the subviews property will return a copy of the array of subviews:

[[someUIView subviews]
 makeObjectsPerformSelector:@selector(removeFromSuperview)];

Thank you to Tommy for pointing out that makeObjectsPerformSelector: appears to modify the subviews array while it is being enumerated (which it does for NSView, but not for UIView).

Please see this SO question for more details.

Note: Using either of these two methods will remove every view that your main view contains and release them, if they are not retained elsewhere. From Apple's documentation on removeFromSuperview:

If the receiver’s superview is not nil, this method releases the receiver. If you plan to reuse the view, be sure to retain it before calling this method and be sure to release it as appropriate when you are done with it or after adding it to another view hierarchy.

Answer 2

In order to remove all subviews Syntax :

- (void)makeObjectsPerformSelector:(SEL)aSelector;

Usage :

[self.View.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];

This method is present in NSArray.h file and uses NSArray(NSExtendedArray) interface

Answer 3

Use the Following code to remove all subviews.

for (UIView *view in [self.view subviews]) 
{
 [view removeFromSuperview];
}

Answer 4

If you want to remove all the subviews on your UIView (here yourView), then write this code at your button click:

[[yourView subviews] makeObjectsPerformSelector: @selector(removeFromSuperview)];

Answer 5

In order to remove all subviews from superviews:

NSArray *oSubView = [self subviews];
for(int iCount = 0; iCount < [oSubView count]; iCount++)
{
    id object = [oSubView objectAtIndex:iCount];
    [object removeFromSuperview];
    iCount--;
}

Answer 6

This does only apply to OSX since in iOS a copy of the array is kept

When removing all the subviews, it is a good idea to start deleting at the end of the array and keep deleting until you reach the beginning. This can be accomplished with this two lines of code:

for (int i=mySuperView.subviews.count-1; i>=0; i--)
        [[mySuperView.subviews objectAtIndex:i] removeFromSuperview];

SWIFT 1.2

for var i=mySuperView.subviews.count-1; i>=0; i-- {
    mySuperView.subviews[i].removeFromSuperview();
}

or (less efficient, but more readable)

for subview in mySuperView.subviews.reverse() {
    subview.removeFromSuperview()
}

NOTE

You should NOT remove the subviews in normal order, since it may cause a crash if a UIView instance is deleted before the removeFromSuperview message has been sent to all objects of the array. (Obviously, deleting the last element would not cause a crash)

Therefore, the code

[[someUIView subviews] makeObjectsPerformSelector:@selector(removeFromSuperview)];

should NOT be used.

Quote from Apple documentation about makeObjectsPerformSelector:

Sends to each object in the array the message identified by a given selector, starting with the first object and continuing through the array to the last object.

(which would be the wrong direction for this purpose)