Using the following code to insert a subview in my UIView I get presented with a black screen. Can someone tell me why?
CJGBoardLabels* whiteLabels = [[CJGBoardLabels alloc] initWithFrame:self.frame
andOrientation:#"white"
andOrigin:self.boardOrigin
andSquareSize:_squareSize
andHorizontalOffset:_horizontalOffset
andVerticalOffset:_verticalOffset];
[self insertSubview:whiteLabels aboveSubview:self];
I get the same result with the following line too:
[self insertSubview:whiteLabels belowSubview:self];
Don't add subviews in the drawRect: method. Instead, use the actual triggering method to add the subviews, and preferably get the controller to add the subviews (not the view itself). So, call addSubview: in the controllers viewDidLoad or an action method.
Related
So, I want to do some basic animations of labels and later views.
I have a label, I'm trying to get it to move when a view loads, so I call the following method at the end of viewDidLoad:
- (void)animateView {
NSLog(#"animateView");
[UIView animateWithDuration:20 animations:^{
// set new position of label which it will animate to
self.dcFirstRunDaysLabel.frame = CGRectMake(20,320,280,215);
}];
}
Instead of animating, the label appears in position.
I've tried every tutorial and read through the docs. I get no errors.
Any thoughts?
Cheers.
Try calling your animateView method in viewDidAppear. Because in viewDidLoad your view isn't visible yet.
viewDidLoad:
Called after the controller’s view is loaded into memory.
viewDidAppear:
Notifies the view controller that its view was added to a view hierarchy.
I had this question when/where to create and initialize views that are created programatically, so I hope some discussions here will shed more light on this topic for me.
This slide:
says: "not to initialize something based on the geometry of the view in viewDidLoad" and suggests viewDidAppear.
Imagine my view controller has view. I want to add 10 dynamic UIButtons to it.
Shall I put the code like below to the viewDidAppear?
-(void) viewDidAppear:(BOOL)animated
{
...
UIButton *button1 = [[UIButton alloc] initWithFrame: rect1];
[self.view addSubview: button1];
UIButton *button2 = [[UIButton alloc] initWithFrame: rect2];
[self.view addSubview: button2];
...
}
But this creates the buttons each time the view is shown. Is it what we want?
On the other hand if I put the code in viewDidLoad slide suggest not to initialize geometry of these views there.
Or shall we create buttons in viewDidLoad and set their frames in viewDidAppear?
What approach do you usually take?
But this creates the buttons each time the view is shown. It's true.
So the best thing you can do is to add a boolean (lets name it isLaunched). You set it to FALSE in the method -(void)viewDidLoad
Then add a if condition in your -(void)viewDidAppear where you perform creation of buttons (or other stuff) and set the boolean to true at the end.
You should have something like that :
-(void)viewDidLoad
{
//some settings
isLaunched = FALSE;
}
-(void)viewDidAppear:(BOOL)animated
{
if(!isLaunched)
{
//creating and adding buttons
isLaunched = TRUE;
}
}
zbMax (and now Amar) offered good solutions to implement the view creations in viewDidAppear: I will provide the rational for doing this (over viewDidLoad).
It is pretty simple actually. In viewDidLoad none of the views are actually setup yet, so any attempt to set/create frames or bounds will be extremely inconsistent. Struts and springs (or autolayout) will take effect after this method which will create additional changes to your views. viewDidAppear: is the correct place to do this because you can now rely on existing views and setting frames.
Reason for not playing with the geometry in viewDidLoad is because view is still in the memory and not on the window. Once the view is put on the window, then you can specify geometry. That happens when viewDidAppear is called for your controller.
As recommended, you should do all the initialisation in viewDidLoad as this is one time task and need not be repeated. Hold references to the added subviews and give them appropriate frame in viewDidAppear.
When you are dealing with custom UIView and its subviews, layoutSubviews is the method you need to override in the custom view in order to rearrange the geometry of its subviews.
Hope that helps!
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 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.
When I want to access the parent UIView of current UIView I declare object of parent UIView in current UIView and access it by assigning the parent UIView object to current view's object property.
Is there any way to get rid of this and directly call the parent view's methods or properties?
I also tried (parentView *) self.view.superview but didn't help.
It gives error while calling function for this object as
[UIVIew unrecognized selector......
If you're calling this directly from a UIView (and not a UIViewController), it should be self.superview instead of self.view.superview.
# Naveed: This is the common code u can use to any view whether it is parent or child view, Just change button name which u want to press and the view name on which u want to go. For example on back button press u want to go on library view then write this code -
-(IBAction)backButtonPressed:(id) sender
{
llibraryView *libraryview=[[libraryView alloc] initWithNibName:nil bundle:nil];
libraryview.modalTransitionStyle=UIModalTransitionStyleCoverVertical;
[self presentModalViewController:libraryview animated:YES];
[libraryview release];
}
Let me know whether ur problem is solved or not.
What I can think is that you want to call the viewcontroller's method from your view, which you added to the viewcontroller's view.
Now you have two options from here, either you set your view controller your view's delegate and then call your viewcontroller's method by [delegate performSelector:] approach.
The other approach is you access your view's superview, and then get it's controller. You can not do that directly, coz if you could do that it would defeat the entire purpose of MVC.
But, still there is a way out, here you go:-
Get to UIViewController from UIView?
Hope, this helps you.