After having spent the whole day looking for a solution I feel only more confused and upset.
Let's face the problem:
I'm developing a single view iOS app made up of an AppDelegate (of course..), A ViewController and a "DrawingClass" (subclass of UIView).
In the main.storyboard i can see my mainViewControllerScene, and inside this main view directed by the viewController, I have inserted a UIView object from the palette in the interface builder and set it to be controlled by my "Drawing class" because I need to use the DrawRect method to draw custom lines.
Well, when starting the app, the defaults lines in my "DrawingClass" are being drawn, so drawrect is being called.
But when, after having pressed a button linked to an IBAction, I try
to call again drawrect through setNeedsDisplay or anything it doesn't
work.
Let's be more clear:
-I'm sure that the view controlled by "DrawingClass" is being drawn correctly on startup
-I'm sure that the IBAction is called (I used an NSLog)
-I can't figure out how to redraw that view. (The one controlled by "DrawingClass")
In the viewController I tried both [self.view setNeedsDisplay] and [myView setNeedDisplay] but none of them called my drawrect method in the "DrawingClass"
What I'm doing wrong? Am I forgetting to init something ? I tried even to call those methods on the main thread but nothing.
I think this question could help many so please ask if you need something more to work out this problem.
Thank you so much.
Related
Across my app I have several different subclasses of UIView: UIDatePicker, UIPicker, UIButton, UITableView, UITableViewCell, UITextView, etc. etc... For each of these I'd like to add a very simple drawRect custom implementation that I have working great.
Is there a simple way to get multiple subclasses of UIView to all have the same drawRect implementation without creating a subclass and repeating the same code across each UIPicker, UIButton, etc. etc... ?
I realize the solution to this is probably to write a delegate class for UIView's layer property and do the custom drawing in drawLayer, but I thought I would ask before I go re-working my code.
The answer seems to be no.
Furthermore, it appears that my idea for the workaround also doesn't work: I was thinking I could write a nice little class that implements the drawLayer method from CALayerDelegate and do the drawing in there, and then in each UIView or UIView subclass' init method do a self.layer.delegate = niceLittleCALayerDelegateClass.
My research, however, happened upon this: https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CALayer_class/#//apple_ref/occ/instp/CALayer/delegate which contains the damning sentence: In iOS, if the layer is associated with a UIView object, this property must be set to the view that owns the layer.
So, double nope.
Against rmaddy's advice I'm going to just write a subclass for each of the UIView subclasses I want to implement this drawing behavior in. We'll see how that goes.
Update:
I can't believe I didn't think of this before, but the "right" way to do this (that is to say without subclassing UIView's subclasses and adding a custom drawRect method to each subclass's subclass), from everything I can find, seems to be to either create a subview or a sublayer with a transparent background that does whatever custom drawing you want.
Obviously this is going to draw on top of the UIView you're actually using, so this would get exceedingly complicated if you're trying to draw things that interact with the default elements of the UIView, but for my purposes (just a simple frame drawn with a UIBezierPath) it seems to work great.
At present I'm not sure if the subview or the sublayer approach is more efficient. If anyone can shed light on that, I'd appreciate it.
I want to design and generate view elements in code, without using storyboard. But I haven't figure out a simple way to locate where should I put my view elements by describing its CGRect. For example, I can drag a button direct into the storyboard and put it where i want, however, in code, I have to write something like
[button setFrame:CGRectMake(24.0f, 113.0f, 271.0f, 140.0f)];
Is there any way or any software can help me?
Your question is a bit broad. You can create your view in code by including in your subclass of UIViewController properties for each subview (control) element and then make all the initialisation in designated initialiser and setting frames and other customisation in viewDidLoad method most likely. But for details where to what set you should go to references for UIViewController lifecycle as it may depend on what you want to achieve. in some cases setting frames in viewDidLoad will be fine whereas sometimes you will need to make some changes in viewDidLayoutSubviews for example.
I have several UITextViews in several ViewControllers. In the past, when I have a couple of instances of needing a custom drawing for a TextView or Label, etc I would just adjust the drawing in viewWillAppear inside the VC that owned the UI object. This time, I will be needed several instances to be customized.
Would it be more appropriate to just create a subclassed UITextView and include the drawing code in drawRect versus having the same drawing code spread around several VC's. I am mainly worried about performance. Code maintainability is a secondary concern though.
To be clear, this is what I would use in drawRect:
- (void)drawRect:(CGRect)rect {
self.layer.cornerRadius = 10;
self.clipsToBounds = YES;
}
So after further testing, initWithFrame doesn't get called, but initWithCoder does. I have also found that initWithCoder is called once and so is drawRect. In my use case (a StaticCellTableView with the UITextView in a cell, what would the difference be?
You can include those 2 lines in init or initWithCoder (In case it's a xib or storyboard) method of the subclassed UITextView.
Basically, this is just properties of the object - the don't need to run every time the UIView needs to refresh itself.
Create a ViewController baseclass, and then use that as the superclass for all your other VCs. You can then add this and other convenience methods to it and share the wealth so to speak.
In this particular case, putting it at the end of viewDidLoad would be a good place, as that is only messaged once, where viewWillAppear may be called multiple times. If you use viewdidLoad the code will be executed once.
I would not put those lines in the view's drawRect since that's called for every refresh. I'd recommend that you subclass UITextView and add those lines to the custom init method.
I've got a view controller xib file with several views in it. I'm building a wizard-type interface. I'm just doing a simple fade between the views, and I'm already using a navigation controller for the main interface. I'd prefer not to use one for this wizard. Anyway, in the views, each panel has at least a button, some sort of input field (usually a UITextField) and some helper text hard coded in a UILabel.
The problem is that not all the UITextField objects are calling the textFieldDidChange method in the delegate (File's Owner - .m file associated with the xib), but all the UITextField objects ARE calling the textFieldDidBeginEditing method.
Makes no sense to me. I feel like I must be missing something simple in how I set up the screens, but I'll be darned if I can figure it out. Each of the screens all look identical in the property sheets (on the right hand side of Xcode), and everything is wired up correctly in the File's Owner property sheet, both in IBOutlet and IBActions.
Here are some shots of what's going on...
Ideas? Thanks.
Here are links to the screen caps of the vital parts.
(being a new member is making it hard to add all the info I need with screen caps!)
As far as I now, there is no delegate method with the header textFieldDidChange. You have created a method of your own, which is depending on a NSNotification. Make sure all the UITextFields are send the right notification.
There is no such method on a UITextFieldDelegate
You may have confused textViewDidChange, which is a delegate method for a UITextView, but itis passed the UITextView that generated the event, not an NSNotification.
Seems like you want textField:shouldChangeCharactersInRange:replacementString: instead.
This is resolved. I'm a knucklehead. :-)
I was attaching my own notifier/observer and hadn't done so for the last few UITextField objects. Sorry to bother y'all.
If I'm creating a UIView programmatically and I wish to change the UIView properties (background, for example, or actually, messing with CALayers), must I place the code outside of UIView such as in the View controller? Can I put the code somewhere inside UIView?
I was checking out the CoreAnimationKioskStyleMenu example, its code is inside UIView but it's loaded from Nib and can be placed at awakeFromNib, so it doesn't seem to apply to my case.
That depends. Obviously, a good way to handle this is to use a xib file, as it is designed to hold data like this, but that isn't always the best answer for every situation.
If the view is meant to be reused frequently (like a button, or some widget) throughout the application, its best to store all that customization in a subclass of the UIView.
If its a single larger view that will always be managed by a UIViewController, you can keep some of the information in the UIViewController. However, if you end up subclassing a UIView anyway it's probably best practice to keep the data in the UIView.
As a general note, I believe its worth your time to push as much of this data into a xib using interface builder. Magic values (like colors or sizes) peppered through your code will always be a problem if you want to modify it. I have found modifying a xib to be much easier.
Actually there are some methods where you could place initialization/ customization code.
(void)willMoveToSuperview:(UIView *)newSuperview;
(void)didMoveToSuperview;
will get called as soon as u add the view as a subview to another view, at which point you already have the frame and all the properties, and you can do further customizing as you wish.
(void)layoutSubviews -- generally used for changing subviews' frames and layout organization.
Will get called each time the view needs to be redrawn by the system, or when you specifically call [self setNeedsLayout] on your UIView.
Hope this helps.