I want to move one view on top of another, how can I know the z index of the view, and how to move on to top?
9 Answers
You can use the zPosition
property of the view's layer (it's a CALayer
object) to change the z-index of the view.
theView.layer.zPosition = 1;
As Viktor Nordling added, "big values are on top. You can use any values you want, including negative values." The default value is 0.
You need to import the QuartzCore framework to access the layer. Just add this line of code at the top of your implementation file.
#import "QuartzCore/QuartzCore.h"
UIView
siblings are stacked in the order in which they are added to their superview. The UIView
hierarchy methods and properties are there to manage view order. In UIView.h:
@property(nonatomic,readonly) UIView *superview;
@property(nonatomic,readonly,copy) NSArray *subviews;
- (void)removeFromSuperview;
- (void)insertSubview:(UIView *)view atIndex:(NSInteger)index;
- (void)exchangeSubviewAtIndex:(NSInteger)index1 withSubviewAtIndex:(NSInteger)index2;
- (void)addSubview:(UIView *)view;
- (void)insertSubview:(UIView *)view belowSubview:(UIView *)siblingSubview;
- (void)insertSubview:(UIView *)view aboveSubview:(UIView *)siblingSubview;
- (void)bringSubviewToFront:(UIView *)view;
- (void)sendSubviewToBack:(UIView *)view;
The sibling views are ordered back to front in the subviews
array. So the topmost view will be:
[parentView.subviews lastObject];
and bottom view will be:
[parentView.subviews objectAtIndex:0];
Like Kolin Krewinkel said, [parentView bringSubviewToFront:view]
will bring the view to the top, but this is only the case if the views are all siblings in the hierarchy.
IB and Swift
Given the flowing layout where yellow is the superview and red, green, and blue are sibling subviews of yellow,
the goal is to move a subview (let's say green) to the top.
In Interface Builder
In the Interface Builder all you need to do is drag the view you want showing on the top to the bottom of the list in the Documents Outline.
Alternatively, you can select the view and then in the menu go to Editor > Arrange > Send to Front.
In Swift
There are a couple of different ways to do this programmatically.
Method 1
yellowView.bringSubviewToFront(greenView)
This method is the programmatic equivalent of the IB answer above.
It only works if the subviews are siblings of each other.
An array of the subviews is contained in
yellowView.subviews
. Here,bringSubviewToFront
moves thegreenView
from index0
to2
. This can be observed withprint(yellowView.subviews.indexOf(greenView))
Method 2
greenView.layer.zPosition = 1
- This method just moves the 3D position of the layer higher (closer to the user) on the z-axis. Since the default is
0
for all the other views, the result is that thegreenView
looks like it is on top. However, it still remains at index0
of theyellowView.subviews
array. This can cause some unexpected results, though, because things like tap events will still go first to the view with the highest index number. For that reason, it might be better to go with Method 1 above. - The
zPosition
could be set toCGFloat.greatestFiniteMagnitude
(CGFloat(FLT_MAX)
in older versions of Swift) to ensure that it is on top.
We can use zPosition in ios
if we have a view named salonDetailView
eg : @IBOutlet weak var salonDetailView: UIView!
and have UIView for GMSMapView
eg : @IBOutlet weak var mapViewUI: GMSMapView!
To show the View salonDetailView upper of the mapViewUI
use zPosition as below
salonDetailView.layer.zPosition = 1
If you are using cocos2d, you may see an issue with [parentView bringSubviewToFront:view], at least it was not working for me. Instead of bringing the view I wanted to the front, I send the other views back and that did the trick.
[[[CCDirector sharedDirector] view] sendSubviewToBack:((UIButton *) button)];