I have created a subclass of UIView and am trying to scale and move the view from within its m file but am running into some problems. When I used the command:
self.frame = CGRectMake(self.frame.origin.x-10,self.frame.origin.y-10,self.frame.size.width/2,self.frame.size.height/2); the object moves location but does not resize (the view only contains a few UIImageViews). In the xib file of the sub class I have the options checked to Clip Subviews and to Autoresize Subviews but neither appears to happen. Any ideas as to why the view will not resize with this command and how I could get it to resize.
Resizing your view is not the same as scaling it. Think of your view as a picture frame. What you're doing above is moving the frame, and also moving the lower right corner (you're shortening the frame's wood bars) - but that does not automatically shrink the picture.
There are four ways of resizing a view with subviews:
Let the superview clips its subviews (by setting view.clipsToBounds = YES): Subviews do not resize or relayout, but only show in the area that is inside the frame.
Let the superview not clip its subviews (by setting view.clipsToBounds = NO): Changing superview size does not have any visual effect on subviews, they also show outside of the frame.
Give the subviews autoresizingMasks: The subviews do not change size, but they relayout according to their autoresizing mask (for instance, a subview may always stay 10 px off the lower right corner of the frame, or may always span exactly the width of the frame.) Note that this does not necessarily automatically scale subview content. Set subview.contentMode accordingly.
Scale the superview: By setting superview.transform = CGAffineTransformScale(superview.transform, 0.5, 0.5), you shrink the superview and all its subviews (you essentially zoom out). Note that this makes superview.frame undefined, which means you shouldn't use that anymore. It can also make things a bit blurry.
You could also "manually" change all the subviews, but that kind of defeats the purpose of having a nice view hierarchy.
As MishieMoo said, temporarily set the backgroundColor of your superview to something visible. This will very likely show you that your view is indeed changing.
Related
I have a UILabel centered within a UIView that expands/contracts depending on the device screen size. I've applied constraints so that the UILabel remains centered no matter the UIView size, which works fine.
Now I'm finding myself resizing the UIView manually like so (where mainView is the View Controller):
self.myView.frame = CGRectMake(0,0,self.mainView.frame.width, self.mainView.frame.height)
So this stretches the UIView to fill the whole screen/View Controller (it's also animated). I assumed the UILabel would continue to centre itself automatically, but it seems to pin itself as though it were constrained to the top of the UIView, leaving a lot of empty myView space below it.
How can I tell the UILabel to remain in the centre of the height-changing UIView that it's in?
We need to see your constraints to help, but:
You need to use centering constraints.
Set the bounds, not the frame of myView.
You might need to call setNeedsLayout on the view of the ViewController you are in
Also, set the background color of the UILabel -- it could be centered, but the text is not centered inside of it. For that, set the alignment properties.
I got a UIView that contains an UIIMageView and several buttons that are allocated on certain position related to the image of the UIIMageView.
The frame of the UIView is (0,0,250,250)
the UIIMageView that is within the UIView is set to autorisizing (all) in IB.
All buttons are set to autoresize (none) and origin middle.
When i change the frame of the UIView i.e (0,0,500,500) the UIIMageView (and image) resize OK but the buttons lose their perspective position by a few pixels (about 2 to 3 in the vertical and horizontal axis).
Is this normal? can someone advise?
Try putting the buttons inside another UIView and then setting the autoresizing options on this new view. You should leave the buttons without autoresizing inside the new view.
there is no answer after all.
I must accept the fact that the resized view and the buttons within it will lose perspective position by 2/ 3 pixels off the x/y axis...
strange....
I have an app that allows a user to drag views onto the screen in multiple orientations. So lets say i'm in portrait mode and my superview is 768x1024. Lets say I drag 10 different items onto that superview. These items are scaled, rotated, etc. Then I rotate the device and my superview shrinks down to 576x768. How do I get all of my subviews to maintain their position and transform relative to the new smaller size? So in essence my superview and all of its subviews should look exactly as they did while in portrait, except everything has been scaled down.
And also, what if im in landscape and everything is "shrunk" down and then I drag another view on and shrink it down to fit well. I would need that new view to scale up in proper place and size when the device is rotated back into portrait
The easiest thing to do here is to use the transform property of your view. In this case, you'd prevent the view from auto-resizing on rotation, and use something like your view controller's willAnimateRotationToInterfaceOrientation:duration: method to set a transform on your superview. You can create a transform with CGAffineTransformMakeScale that will scale up or down all of your content; you'll probably want one for landscape and just use a nil transform for portrait (or vice-versa).
This will complicate dragging new views into your superview, since it's transformed, but once you've got views in there, they should behave correctly when resizing. For new views, you'll have to compute (perhaps using convertRect:fromView: method of UIView) what a rect will be once you add a new subview.
You can also override your view's layoutSubviews() directly and assign your subview's transforms based on your view's dimension. This way, you can still get the benefits of using Auto Layout with your view and potentially other sibling UI items, while you customize subview's frames and/or transforms manually without Auto Layout.
I have a UIImageView that I create progmatically right? Works like a charm when I initWithImage and set the parameters for scaling to UIViewContentModeScaleToFill. I can scale all day long and create many different smaller 'thumbprint' sized versions of the UIImageView at whim, HOWEVER when I add subviews to said UIImageView and then try to scale the happy new parent the child subview does not scale! I looked around and found that I should enable the setAutoresizingSubviews boolean of the parentView to true (Which I did) and then call:
ChildView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
Which I also did... now when I scale the parent view the child also scales but crazy wacked out like and goes all over the place (Not a very good way of putting it) but my point is that I assumed the child would scale proportionally to the parent and stay in the same place (Which it doesn't)
My question is how do I set up my code so that when I scale my parent view by 1/4 or w/e to make a thumbprint of the view the children subviews that the parent view owns will scale accordingly and allow the 1/4 sized thumbprint to look just like the full sized view (Just smaller).
To scale subviews, you need to set the affine transform of the view to scale the contents instead of using the content mode.
The autoresizing mask isn't for scaling subviews. Instead, it's a springs-and-struts model for how to position and resize the frame of subviews when the parent view is resized. Mostly it's used when the view autorotates from landscape to portrait and vice-versa.
What you're trying to do is scale the content of the view. So instead of using UIImageView, which is optimized for displaying images, I would create a custom subclass of UIView, and then in the initialization, set the view's transform with this code:
self.transform = CATransform3DMakeScale(zoom, zoom, 1.0f);
Then put the subviews in. You can re-set the transform and the subviews will stay in the same positions relative to each other, but at a different scale.
I created a UIView xib in Interface Builder and tried everything I could to indicate that the UIView should center itself, anchor itself at center, orient itself in central coordinates, etc. etc.
But whenever I add it as a subview in code, I also have to programmatically set its frame up with CGRectMake() or else it will always add to the top-left of its parent. The math to reframe it is pointless and ugly, so I presume I'm just not twiddling a bit in the IB inspector correctly.
Can anyone confirm this is possible, and if so, what I need to do in IB to accomplish this?
Why don't you just set .center of the subview just added, to be the point created by halving the width and height of the superview?
Either that or define the rectangle that view is going into with IB (I'm imagining a container view) and simply set the frame of the view you are adding to containerView.bounds (bounds is a position independent value and so x,y will be 0 while size will equal the container size.
Centering but maintaining size isn't possible in IB. Centering but maintaining margins to its superview is though.
You will have to override the layoutSubviews message or simply keep the calculation code you wrote.