I'm trying to switch between two views right now. The problem is how it is called.
Heres the easiest way to explain my situation:
I have a Parent View.
With a subclass ChildView, that contains a table.
Upon selecting an object in that table, I wish to switch to a different child view of that parent view.
Parent---------
|Child 1 |Child 2
Child 1 is a subclass of Parent to allow me to access a method in Parent that switches between Child Views 1 and 2, but for some reason it wont work when accessing it from Child 1.
Any clues on how to do this? Heres the basic code:
Child 1
- (void) changeViews
[super methodToSwitchChildViews];
Parent
- (void) methodToSwitchViews
[self.child1.view removeFromSuperView];
[self.view insertSubView:child2.view atindex:0];
Super is the class that precedes a (sub)class in inheritance. Here the children seem to be views on a superview (parent). So use superview, and not super.
Okay, I dug around quite a bit and finally figured out a solution. In case anybody ever has the same problem here's what you do:
In the .h file of the child view do
#class parentViewName
Then in the .m file add
#import "parentViewName.h"
...
- (void) functionToRemoveSelfFromView {
parentViewName *PARENT = [[parentViewName alloc] init];
// You must have a method in the parent view to toggle or remove the subview, the way
// you want it done, then call it with the new delegate. Make sure it doesn't set this
// view to nil or releases it because this method has yet to return. If animating do not
// hide this view either.
[PARENT methodToRemoveSelfFromView];
[PARENT release];
}
Related
I'm building an app which consists of different views which are closely related to each other. So far, I only have one UIViewController which controls these different views. View 1 and 2 share the same background, for instance, and the transition between view 1 and 2 is a custom animation.
My problem is that both view 1 and 2 have an UIScrollView. My UIViewController is their delegate and I could have the following scrollViewDidScroll to distinguish between the two scrollviews:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (scrollView.tag == 1)
//handle a
else if (scrollView.tag == 2)
//handle b
else if (scrollView.tag == 3)
//handle c
}
As a lot happens with scrollView 1 and different things happen with scrollView2, the code will become really messy. Ideally, I'd like to define in a separate file what happens if scrollView1 is scrolled etc.. Yet I don't want to have another UIViewController as then transitions become more difficult. I don't have a NavBar or ToolBar, so neither UINavigationController nor UITabBarController would work very well in my case.
What should I do?
I posted a similar question here.
If you don't want two view controllers, just create a separate delegate for each scroll view. Make it an NSObject which conforms to UIScrollViewDelegate and create it at the same time as the scroll view.
Seems to combine the results you seek: one view controller, but encapsulated scroll view code.
You could have a base controller class that handles the common functionality. Each different controller can inherit from this and override with their specific functionality as required.
Aka the template pattern
Edit
To expand. You say you want only one view controller. So you should create a separate class to handle the individual functionality. The View Controller has a base class pointer which gets swapped around according to the current view.
In pseudo code :
class BaseFunctionality
-(void) handleDidScroll {}
end
class ScrollViewAFunctionality : BaseFunctionality
-(void) handleDidScroll {
// Lots of interesting technical stuff...
}
end
class ScrollViewBFunctionality : BaseFunctionality
-(void) handleDidScroll {
// Lots of interesting technical stuff...
}
end
class TheViewController : UIViewController
BaseFunctionality *functionality;
-(void) swapViews {
// Code to swap views
[this.functionality release];
if (view == A)
this.functionality = [[ScrollViewAFunctionality alloc] init]
else if ( view == B)
this.functionality = [[ScrollViewBFunctionality alloc] init]
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
[this.functionality handleDidScroll];
}
end
I am trying to create a custom UISlider. I need to insert subviews (like a label) to self. I'm using the
[self insertSubview:_label1 atIndex:2];
method to do so. Everything works fine when I create my slider in IB and assign my PWSlider class to it.
However, if I try to create my PWSlider from code, there are no subviews present when I do my inits (adding my subviews).
For the init in code I override initWithFrame, for the NIB-case I tried both, awakeFromNib as well as initWithCoder - same result.
When I debug with
NSLog(#"subview count: %d", [self.subviews count]);
the result is that loaded from NIB I get 3 subviews, loaded programmatically I get 0.
Any ideas?
I assume your PWSlider is inherited from UISlider and also assume you have code which is something like:
-(id)initWithFrame:(CGRect)r {
self = [super initWithFrame:r];
if(self) {
// add your subviews here, starting from index 0
}
return self;
}
Did you debug and check that your initWithFrame gets called?
Also, if you don't care at which locations your subviews are, use addSubview instead of insertSubview:atIndex:.
I have 5 different views and when I tap the button, I want to push one of 5 views randomly. However, I do not want to make 5 different controllers for each views. Do I have a chance to put them in one controller? If so, how?
You can have as many views as you want in a single UIViewController subclass. You can create them all in Interface Builder as well, in the one .xib file for your UIViewController class (it might get a bit hard to see, though, better to lay out each UIView in its own .xib). You can present them in any combination you want. Assuming you want to just show one view at a time, you can do this:
In your viewDidLoad method, start out showing the initial view, and in your class keep track of which is the current view:
...
#property(nonatomic, retain) UIView *currentView;
...
- (void)viewDidLoad
{
[self.view addSubview:self.defaultView];
self.currentView = self.defaultView;
}
Then to switch to a particular other view do this:
- (void) switchToView:(UIView *)newView
{
[self.currentView removeFromSuperView];
[self.view addSubview:newView];
self.currentView = newView;
}
}
Or you can show them all at one time: just [self.view addSubview:theView];
You have to set the tags of all the views, and then use
int r = arc4random() % 5;
method to find the random number. Use this newly generated number to check the tag, in your selector
Just change the view outlet of the controller on the action of the button. Use random numbers to select which view. Ouh and - (void)setNeedsDisplay :)
I want to change an image on a view, from a popup dialog of 4-6 icons (imagine like changing your image on a messenger application).
The way I implement this modal popup is by creating a new view at IB, with opacity on the background, and then I load this as a subview:
IconsViewController *iconsViewController = [[IconsViewController alloc] initWithNibName:#"IconsView" bundle:nil];
[self.view addSubview:iconsViewController.view];
So, when the user touches an icon, I have
- (IBAction)iconIsSelected:(id)sender {
switch ([sender tag]) {
case 1:
[(ParentViewController*)[self superview] changeIcon];
break;
case 2:
// same here..
break;
default:
break;
}
[self.view removeFromSuperview];
[self release];
}
The changeIcon just sets the image to a corresponding icon.
As you can guess, this is not working - the changeIcon message never works.
I can't understand what am I doing wrong, any help much appreciated!
You have a few choices here...
First one is create a property on your IconsViewController of type ParentViewController*, for example:
#property (readwrite,nonatomic,assign) ParentViewController* parentController; // weak reference
To break this down further:
readwrite because we want to be able to access the value via [self parentController] but also change it via [iconsViewController setParentController:self]
nonatomic because I'm not too worried about threading
assign to make it a "weak reference" where the parent will not be retained by the child. If they each retain the other, it could lead to memory leaks later because unless explicitly released you'd end up with a retain circle causing neither object to hit a zero retain count.
When you load from nib, set the property:
IconsViewController *iconsViewController = [[IconsViewController alloc] initWithNibName:#"IconsView" bundle:nil];
iconsViewController.parentController = self;
Then, call to it from inside of iconIsSelected like this:
[[self parentController] changeIcon];
Alternatively, you can create a delegate protocol:
#protocol IconViewSelectedDelegate (NSObject)
- (void) changeIcon;
#end
And use that protocol as a property, instead of the parent view controller type. This is more abstract, but it keeps the design cleaner. The parent view controller would then implement that delegate protocol, as one of many others.
Another option is to use NSNotificationCenter and publish/subscribe to events from your dynamic view. This is the "loosest" coupling between the two objects, but it might be overkill for this scenario.
The superview of a view is a view, not a view controller, yet you cast the superview to be of class ParentViewController. If the view has no superview, it returns nil, and message to nil are no-ops (which explains why you don't crash there).
BTW, that [self release] at the end is highly suspicious.
I have an array of booleans (soundArray) that is modified based on user input. Therefore it is owned by the main UIView that the user is interacting with. Meanwhile, in another separate controller (GestureController), I need access to this soundArray, so I can pass it as a parameter in a method call.
I'm pretty sure a ViewController shouldn't be digging out properties of a UIView it doesn't own (correct MVC), so I've created another pointer to the soundArray in the ViewController (MusicGridController) that owns the main UIView (MusicGridView).
In GestureController, I have the following code:
// instantiate the sound thread
NSArray *soundArrayPointers = [NSArray arrayWithObjects:self.musicGridViewController.soundArray, nil];
[NSThread detachNewThreadSelector:#selector(metronome:) toTarget:[MusicThread class] withObject:soundArrayPointers];
(eventually I'll have more soundArrays in that array).
Now, in MusicGridController, I need to set the pointer to the SoundArray in the UIView MusicGridView... so I did this:
- (void)viewDidLoad {
[super viewDidLoad];
self.view.frame = CGRectMake(20, 0, 480, 480);
MusicGridView *tempview = self.view; // this line gives me a warning that I am initializing from a distinct Objective-C type, which I don't understand.
self.soundArray = tempview.soundArray;
}
I tried self.soundArray = self.view.soundArray, but it threw an error, and I don't understand why. So my question is: Is this a correct implementation? How do I get from one viewController to a property of a given UIView?
I'm not sure I understand who the NSArray belongs to, or who it should belong to, but you can try utilizing the AppDelegate if it's supposed to be a global object (accessed by more than one view and/or controller).
Now, to solve your problem. Your implementation is not wrong, and the warning will go away if you add (MusicGridView *) before self.view. This is related to the error you got when you tried self.soundArray = self.view.soundArray, and the reason is simple: UIView doesn't have a soundArray property, and self.view is a pointer to a UIView. By casting self.view to a MusicGridView *, you get rid of the warning, and your code should work fine.