I have a class that subclasses UIView called DrawView. This class contains custom drawing in the drawRect: method. I want to add this to a UIScrollView programmatically in a UIViewController class controlling the view which the UIScrollView has been added to. Also, I want the instance of DrawView to be a global variable.
I kind of confused and I am not really sure of anything, except that at some point I will have to call [scroller addSubview:drawViewInstance];. Thanks
Yes what you have written is correct. Also your subview should be a new class overriding the methods you need. You can maintain it globally by providing a method to return the instance more like a singleton.
Put the variable into the app delegate class. Alloc and init it and you can access it using the getter. Declare the variable in your delegate.
[UIApplication sharedApplication].delegate].globalInstance;
Related
I have a subclass of UIViewController that I want to add from the storyboard.
So I'm using what seems the standard methodology:
SubViewController *svc = [self.storyboard instantiateViewControllerWithIdentifier:#"SubViewControllerID"];
[self addChildViewController:svc];
[self.view addSubview:svc.view];
Which is fine but what if I want to call a custom init method on the subview?
I can do something like:
svc = [svc initWithFoo:#"Hello"];
Which seems to have to go after the addSubview call inorder for it to work.
Is this the best way to do this?
Seems a bit unorthodox. Calling an init method on an object that has already been created seems like its no longer truly an init method.
Maybe I should call it setWithFoo: or something and not have it return anything?
SubViewController *svc = [self.storyboard instantiateViewControllerWithIdentifier:#"SubViewControllerID"];
will cause the SubViewController to be inited with it's - (id)initWithCoder:(NSCoder *)decoder {} method.
Override that method (don't forget to call super)
If you want to do additional setup to your view controller after you instantiate it form the storyboard you can create some methods in the view controller's class and call them after the instantiate method fo the storyboard.
But be careful, if you try to make changes on any UI component in those methods, they wont be applied, and probably the app will crash. So use those methods to set params to the View Controller like array of objects, or any kind of data, and apply the UI changes for the view controller's view in viewDidLoad/viewWillAppear/viewDidAppear methods of your view controller.
Essentially I think the answer is that you can't use custom initialisers on ViewControllers added from the storyboard. Instead you have to set properties directly or through a method at the appropriate time in the life cycle as stated above.
Also as mentioned, the VC will be instantiated through initWithCoder, so calling an additional initialiser might be superfluous(?).
I encountered problems trying to use a custom initialiser that contains a call to super if I called it before the subview was added. I would just get a blank view added, I think because the superclass doesn't seem to know about the storyboard at that point. I had more success removing the call to super but that seems wrong.
This case would be more pertinent when adding subviews to a scrollview. For simplicity I left this out of my example.
I guess this is basic, but I can't get my head around this.
I used to have only one ViewController in which all my variables were defined, e.g. an UITextView named myTextView. I also had methods in this ViewController for handling events that relate to myTextView, such as - ()hideKeyboard { // do something with myTextView or - (void)keyboardWillShow:(NSNotification *)notification { // do something with myTextView.
As my program became bigger and bigger, I thought about using subclasses, especially for other views. So I started a subclass, eg. mySubClass.h and mySubClass.m, in which I had another UITextView (for argument's sake myOtherTextView). In order to incorporate mySubClass, I #imported it into my ViewController and added a #class mySubClass; and could then produce instances of this class so as to use it in my App.
So far so good. As you can imagine, all the nice methods I defined in my ViewController for what should happen when an UITextView is edited (such as hiding keyboard etc.) didn't work for the UITextView in mySubClass.
It was then suggested to me that I should make another class in which I had all the keyboard events and subclass my ViewController and mySubView to it:
#interface ViewController : MyKeyboardEventsViewController
Now, the problem I am seeing is that I won't be able to access all the views, textviews, textfields etc. that I have created in my ViewController (e.g. myTextView which I mentioned earlier).
How can I achieve that all the variables that I have defined in my ViewController will also be available for MyKeyboardEventsViewController? Or is there another way to handle this?
Basically, I don't get how MyKeyboardEventsViewController will be able to access variables in my ViewController which it will need (e.g. the UITextView in question, or the accessoryView which will pop up etc. etc.).
Any suggestions would be very much welcome.
Example:
Class A contains a ivar UITextField textField
Class B subclasses Class A and thus it already contains ivar textField
Note: it's not the other way around. Class A does not "see" what ever is created in Class B.
When ever you subclass a class you give your new class the same ivars end methods of that subclassed class.
I hope this is what you were asking for.
EDIT
So for your example I would do the follwing:
Create a class "MyUIKeybordEventResponder"
Implement all the responder methods like - (BOOL)textFieldShouldReturn:(UITextField *)textField
Subclass your ViewController from "MyUIKeybordEventResponder"
Note method textFieldSHouldReturn has a parameter UITextField so it knows which textfield was pressed. So in a way it receives your textField from the subclass.
If I'm understanding this correctly, you have a UIViewController with MyKeyboardEventsViewController as an instance variable and you want to communicate between the two? If that is the case, one option would be to create a protocol.
#protocol MyKeyboardDelegate
- (void)closeAccessoryView;
#end
(Note - make whatever methods in the protocol that you need, this is simply an example)
In your MyKeyboardEventsViewController you then include the protocol file, and create an ivar
id <MyKeyboardDelegate> delegate;
Also make it a property and synthesize it.
Whatever class that is going to create the keyboardviewcontroller should delcare themselves as conforming to the protocol.
#interface MyViewController : UIViewController <MyKeyboardDelegate>
...
#end
When you create the MyKeyboardEventsViewController, set the delegate.
MyKeyboardEventsViewController *eventsVC = [[MyKeyboardEventsViewController alloc] init];
[eventsVC setDelegate:self];
Now just implement the delegate method and perform whatever action that is necessary.
hope someone can help me on this as been stuck for hours.
I am trying to make a kind of picture book.
I have a view which is my container and I add subviews to that by using addsubview.
On the subview, I have swipe gestures etc that I want to trigger off method in the parent view. I worked out how to trigger the delegate but I cant get the delegate to trigger the parent view. I have read over 10 different ways of doing it and none work.
I now very confused about what a super view is to. Just to confuse matters, the delegate has a tabcontroller and the parent view is tab button 1
I tried
[self.view.superview method]
[self.superview method]
On the delegate I tried
self.tabcontroller.parentviewcontroller, selectedview, super view.super
UPDATE :
The subview needs to be independant of the parent view as its a reusable view.
Also I have not set the parentview to superview as I just thought a superview is a view with subviews (please don't kill me). So maybe I just need to set the parentview to a superview?
The proper way of doing such things is to use protocol and delegate pattern.
Define a protocol like
#protocol subViewDelegate
-(void)somethingHappened:(id)sender;
#end
then implement that protocol in your superview :
#interface superView:UIViewController<subViewDelegate> {
...
}
...
#end
define a delegate property in your SubView like this
#interface subView : UIView {
id<subViewDelegate> delegate;
...
}
#propery (nonatomic, assign) id<subViewDelegate> delegate;
...
#end
the in your subview, call the delegate like this
[self.delegate somethingHappened :self];
It's a little hard to help you without any code given, but let's try:
Create a protocol: Name it however you like (I will call it "MyProtocol") and add to it the definition of the function you want to call in your superview, let's call it "respondToSwipe"
If your superview is a UIView, you have to create your own subclass of UIView and make your superview an instance of that class.
Let your (newly) created superview class implement the protocol of 1.) an implement the "respondToSwipe" method
Create an instance variable of the the type id in your subview, and name it however you like, e.g. "myDelegate".
Pass the superview created in 2/3.) to your "myDelegate" variable
Call [myDelegate respondToSwipe] whenever you like
For a custom view, you could subclass UIControl and use control events:
Define some control events. You're free to make up 4 control events (UIControlEventApplicationReserved = 0x0F000000)
Have whoever wants to receive events call addTarget:action:forControlEvents:
Have the control call [self sendActionsForControlEvents:events]
Alternatively, you could use a UIGestureRecognizer-style interface (addTarget:action:).
Alternatively just use UIGestureRecognizer (OS 3.2+)
Did your parent view set itself to be the superview of the subview when it added the subview? Otherwise the subview doesn't know who its superview is.
The more standard way of naming things to call the method handler the delegate instead of the superview, make it a property, and have the subview check for both the existence of the delegate being set and whether it can handle the method.
Here a very good example of how apply the delegation pattern on the iPhone. I downloaded the code an it works pretty good.
http://www.hivestudio.cat/index.php?option=com_content&view=article&id=57:technical-note-the-delegation-pattern-on-the-iphone&catid=35:technical-note-category&Itemid=76
I messing with iphone developement. I have a uiimageview subclass that I want to use to detect touches. I have sucessfully added to interfacebuilder and I can detect a touch in my UIImageview subclass within my application so all is good on that front. however my UIImageView subclass has a custom initializer which is not called when it is created in interface builder.
if I manually initialize the UIImageview and add it programmatically I think it will work but then I lose the ability to 'see' my positioning in Interface builder.
how can I either
1) 'see' a uiimageview in interface builder that is added in code? (not possible?)
2) call my custom initializer when the subclass is instantiated in interfacebuilder.
thanks
Hi thanks for suggestions. I think I'm getting closer to understanding the relationship between the xib and the viewcontroller.
I now am sucessfully adding my UIImageView subclass programmatically and using my custom initiializer which overrides InitWithFrame.
I think I read that the xib calls 'awakeFromNib' so I could equally add my iniitialization code in there. I like the idea of adding it programmatically as I have more control (although harderto set up my IU)
so one more realted question. if I add an UIImageView subclass in interface builder. I can see it and detect touches on it. if I want to refer to it in the view controller class do I have a pointer to it? i.e. is there a variable name for it? the UIImageViews I create myself I obviuosly know what they are called.....
You likely have put your instructions in the wrong initializer.
According to the documentation, objects unarchived from a NIB are initialized with initWithCode: if they conform to the NSCoding protocol; objects that don't conform to NSCoding are initialized with init.
In this particular case, UIImageView does conform to NSCoding. It's likely that you have you intended for initWithFrame: to be called and put your instructions in that method.
Can you not simply put your initialisation logic in viewDidLoad? In particular,
-(void)viewDidLoad {
[super viewDidLoad];
// Put whatever was in your custom initialiser here.
}
I've created a view controller and the associated view using the interface builder. I'm trying to call a function that I added to the UIView from the UIViewController. I'm not sure how to call that function though.
I've tried
[self.view myFunction]
but that just makes my program crash.
Did you declare your IB outlets and connect the method to it?
Your view (more accurately nib)'s file owner should be set to your viewController class.
Unless your calling drawing functions and methods you shouldn't call anything on the view. You just don't need to.
Edit: grammar corrections.
How is the view getting initialized? Is it a custom view type? If your view is being initialized from a nib, make sure that the class on the view type is the class that has the method implemented.
It is probably crashing because UIView does not have a method named myFunction. In order to add myFunction to a UIView object, you need to subclass it.
I assume you have subclassed your UIView, and called it something like MyView. You also probably have subclassed your UIViewController and called it MyUIViewController. Therefore you may have:
#interface MyViewController : UIViewController {
MyView *myView;
....
}
Now you can call [self.myView myFunction];
That's one way. Another way may be:
[(MyView *)self.view myFunction];
This depends on whether myView is the first view in the hierarchy (or should be set up in your NIB files).