Can UIView be copied?
IosObjective CUiviewCopyIos Problem Overview
Simply using this way:
UIView* view2 = [view1 copy]; // view1 existed
This will cause simulator can not launch this app.
Try retain,
UIView* view2 = [view1 retain]; // view1 existed
// modify view2 frame etc
Any modifications to view2
will apply to view1
, I understand that view2
share same memory with view1
.
Why can't UIView
be copied? What is the reason?
Ios Solutions
Solution 1 - Ios
this might work for you ... archive the view and then unarchive it right after. This should give you a deep copy of a view:
id copyOfView =
[NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:originalView]];
Solution 2 - Ios
Your app probably crashes with something like:
[UIView copyWithZone:]: unrecognized selector sent to instance 0x1c6280
The reason is that UIView does not implement the copying protocol, and therefore there is no copyWithZone
selector in UIView.
Solution 3 - Ios
You can make an UIView extension. In example swift snippet below, function copyView returns an AnyObject so you could copy any subclass of an UIView, ie UIImageView. If you want to copy only UIViews you can change the return type to UIView.
//MARK: - UIView Extensions
extension UIView
{
func copyView<T: UIView>() -> T {
return NSKeyedUnarchiver.unarchiveObject(with: NSKeyedArchiver.archivedData(withRootObject: self)) as! T
}
}
Example usage:
let sourceView = UIView()
let copiedView = sourceView.copyView()
Solution 4 - Ios
for swift3.0.1:
extension UIView{
func copyView() -> AnyObject{
return NSKeyedUnarchiver.unarchiveObject(with: NSKeyedArchiver.archivedData(withRootObject: self))! as AnyObject
}
}
Solution 5 - Ios
UIView
doesn't implement the NSCoping
protocol, see the declaration in UIView.h:
@interface UIView : UIResponder <NSCoding, UIAppearance, UIAppearanceContainer, UIDynamicItem, UITraitEnvironment, UICoordinateSpace, UIFocusEnvironment>
So, if we want to have a copy
like method, we need to implement the NSCoping
protocol in a category or so.
Solution 6 - Ios
You can make method something like this:
-(UILabel*)copyLabelFrom:(UILabel*)label{
//add whatever needs to be copied
UILabel *newLabel = [[UILabel alloc]initWithFrame:label.frame];
newLabel.backgroundColor = label.backgroundColor;
newLabel.textColor = label.textColor;
newLabel.textAlignment = label.textAlignment;
newLabel.text = label.text;
newLabel.font = label.font;
return [newLabel autorelease];
}
Then you can set your ivar to the return value and retain it like so:
myLabel = [[self copyLabelFrom:myOtherLabel] retain];