CustomView *customView = [...];
[self.view addSubview:customView];
I need to detect in my CustomView class when it is added in other views or when my superview changes.
You can use willMoveToSuperview: and didMoveToSuperview to detect when the view is moved around. layoutSubviews will be called when the superview changes frame.
For a UIView use - (void)didMoveToSuperview
For a UIViewController use -(void)viewWillAppear:(BOOL)animated
also assign THE TAG of Customview before addsubview and the detect by Particular TAG.
Related
I have a very simple UIView, that is only drawing a triangle. It implements a UIView drawRect method that is drawing a figure. It is working fine on iOS7, but when I run the same code on iOS8 it is not even called. Any ideas what has changed on iOS8? My code in nutshell:
#interface MyView : UIView
#end
#implementation MyView
- (instancetype)init {
self = [super init];
if (self) {
self.backgroundColor = [UIColor clearColor];
}
return self;
}
- (void)drawRect:(CGRect)rect {
// draw things
}
#end
myView = [MyView new];
[self addSubview:myView];
Update
My view hierarchy: UIViewController View->Custom UILabel->MyView
It is an error message bubble, and my view is a beak pointing to something.
I have used a new UI debugging tool, but it is not visible there. Init method is called, drawRect is not. Something must have changed in iOS8, because iOS7 is calling drawRect.
Update 2
Of course I'm using constraints (and Masonry pod), and this is why I did not specify the frame.
[myView mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(make.superview.mas_bottom);
make.centerX.equalTo(make.superview);
make.width.equalTo(#10.0f);
make.height.equalTo(#5.0f);
}];
I have also tried adding [myView setNeedsDisplay] in various places, but it didn't help.
Problem finally solved. I'm not sure what exactly caused the issue (Masonry [constraints framework] or iOS8 changes to UILabel), but the solution was to change the view hierarchy. I created another UIView that contains both UILabel and my UIView (drawn beak) instead of adding the UIView to UILabel as subview. Now drawRect method is called both on iOS7 and iOS8.
Previous hierarchy:
UIViewController View->Custom UILabel->MyView
New hierarchy:
UIViewController View->Container UIView->Custom UILabel & MyView
To sum up, if your drawRect method is not called on iOS8, and you are adding some UIView to UILabel as subview, try to use some container which will contain both UIView and UILabel.
make sure that myView's superview property clipToBounds = NO, and that myView rect is on screen
There is an important detail missing in your approach. You need to specify a frame that determines the origin and size of your view. This can be done with the initWithRect method of UIView, or you can set the frame after allocation/initialization. Since you have a custom init method already I would do the following:
myView = [MyView new];
myView.frame = CGRectMake(0.0,0.0,100.0,100.0);
[self addSubview:myView];
This will draw your custom view with an origin point of (0.0,0.0) and a width and height of 100.0.
Furthermore, adding a call to setNeedsDisplay should force the drawRect method to be called if you are still having trouble:
[myView setNeedsDisplay];
I have added a view inside ViewController using [self.view addSubview:newView]. newView is a UIView type object.
Inside newView I added added a few views using [self addSubview:polyg];.
Polygs also inherit from UIView. But they never get drawn. drawRect:(CGRect)rect is never called.
I'm new to iOS and have no idea what I'm doing wrong.
It probably has something to do with the fact that I did not use self.view when adding views to newView. I can't even use self.view inside newView.
how can I make this work?
edit:
When i create these polyg objects I'm using initWithFrame and sending newView's frame, like this: [[Polyg alloc] initWithFrame:self.frame];
Could this be the cause? Polyg is going to be a movable and resizable polygon, so I figured each should be able to draw on the entire screen.
edit:
I created a method inside newView called touchX:Y that is called from the viewController whenever I touch my finger on the screen. Inside I wrote this: NSLog(#"subview = %i", self.subviews.count);. Whenever I touch the screen I see this on the console: subview = 89 so I'm pretty sure the subviews were added to newView.
I tried adding this to the same touchX:Y method:
for (UIView* subview in self.subviews) {
[subview setNeedsDisplay];
}
But the subviews' drawRect is never called.
The most likely possibility is that newView is either completely off the screen or have a size of (0,0). Right before you add the ployg subviews, use the debugger to print out the frame of newView.
I have a UIScrollView, created programmatically, inside of a UIView. What do I need to do to ensure that I can use the delegate method scrollViewDidEndDecelerating?
Here's what I have set up, please assume that within the UIScrollView, that there are three UIImageViews. When the page first loads, I am looking at the center UIImageView and I can scroll once backwards or once forwards. The reason why I need this delegate method is because I intend to use it to calculate which UIImageView I am currently looking at.
ViewController.h
#interface ViewController : UIViewController <UIScrollViewDelegate>
ViewController.m
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
scrollView.pagingEnabled = YES;
[self.view addSubview: scrollView];
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
NSLog(#"scrollViewDidEndDecelerating");
}
Add
scrollView.delegate = self
after the scroll view initialization.
In your delegate method, you can test each uiimageview center to see Which one match the uiview center, That's the uiimageview you are looking at.
I want my UIView subclass to position itself automatically when it is added to a parent container view.
Can I somehow detect when it is added and run my positioning code then or do I need to do something like?
[parentView addSubview:subView];
[setView calcPosition];
UIView provides the methods willMoveToSuperview: and didMoveToSuperview. Just override those to know when the view is added to another view (or later removed).
Write calcPosition methord inside the subview and call it from the didMoveToSuperview of subview
- (void)didMoveToSuperview
{
[super didMoveToSuperview];
[self calcPosition];
}
I have a custom UIView that I need to add as a subview in a UIViewController.
But if I use [self.view addSubview:newView]; the app goes in a infinity loop and doesn't start. But if I use self.view = newView then it works. But I need it as a subview.
The UIView contains a grid layout of custom button.
I guess you do that in the loadView method. You must not call the view method of the view controller in loadView because that will itself call loadView! However calling setView: (e.g. self.view = newView) is okay.
My suggestion is to add the subview in viewDidLoad.