I'm somewhat puzzled by object lifetimes under ARC. Here’s a scenario which I think is probably common.
1) In response to some event, was load an NSViewController from a nib.
- (IBAction) doIt: (id) sender
{
InfoController *editor=[[InfoController alloc]initWithNibName:#"InfoController" bundle:nil];
[editor show: .... ]
}
2) The InfoController then displays an NSPopover.
3) Sometime later, the user clicks outside the NSPopover. The popover closes itself.
But when does the InfoController get released? For that matter, what's keeping it alive after doIt returns? In my implementation, InfoController is a data source and delegate for controls in its NSPopover, but in general data sources and delegates aren't retained, right?
I realize your question is a bit old now, but I came across it while researching a retain cycle with my NSViewController and NSPopover:
The NSPopover contentViewController property is retaining your NSViewController. That is why you can show the popover like you (and I) do as a response to an action, without another object retaining it. What I found though, is that to properly release the NSViewController under ARC, the contentViewController should be set to nil when the popover is closed. This is in my NSViewController subclass:
- (void)popoverDidClose:(NSNotification *)notification
{
self.popover.contentViewController = nil;
}
Related
I'm new to Xcode and objective c. I want to create a button (probably a UIBarButtonItem, for a navigation bar) with a particular appearance, which I will use repeatedly in different views. I've searched at length but can't figure out how.
Would it be appropriate to subclass UIBarButtonItem? I tried to do that, but I was quickly in over my head. Once I create the .h and .m files as a subclass of UIBarButtonItem, do I then have to instantiate a UIBarButtonItem? Do those files not automatically create a button object for me (imported from the parent class), which I can refer to as self? It seems like it would be weird to instantiate a button within its own subclass.
One thing I want to do is add the line,
button.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;
but I'm at a loss as to how to create reusable button with that property.
Even if that is completely the wrong approach to creating a reusable custom button, I clearly need to improve my understanding of objects, so explanation of my misunderstandings would be much appreciated!
Please?
You can do this without subclassing - by making a category (a preferred way of doing things in Objective-C). With a category you can provide custom methods for an object without having to subclass it. You can't (easily) provide custom properties, but in your case this is not relevant.
Using a Category
This is how your category header file could look:
// UIButton+StyledButton.h
#import <UIKit/UIKit.h>
#interface UIButton (StyledButton)
- (void) styleButton;
#end
Then in the implementation file:
//
// UIButton+StyledButton.m
//
#import "UIButton+StyledButton.h"
#implementation UIButton (StyledButton)
- (void) styleButton {
//style your button properties here
self.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;
}
('self' refers to the button object, which also acquires the custom methods you write in the category.)
To use it, #import "UIButton+StyledButton.h" then you can do this sort of thing...
on viewDidLoad {
[super viewDidLoad];
UIButton* myButton = [[UIButton alloc] initWithFrame:myFrame];
[myButton styleButton];
}
Using a Subclass
The subclassed equivalent would look something like this:
The header file...
// MyCustomButton.h
#import <UIKit/UIKit.h>
#interface MyCustomButton : UIButton
- (id)initWithCoder:(NSCoder *)coder;
- (id)initWithFrame:(CGRect)frame;
#end
The implementation file...
// MyCustomButton.m
#import "MyCustomButton.h"
#implementation MyCustomButton
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self styleButton];
}
return self;
}
- (id)initWithCoder:(NSCoder *)coder
{
self = [super initWithCoder:coder];
if (self) {
[self styleButton];
}
return self;
}
- (void) styleButton {
//style your button properties here
self.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;
}
You provide two init methods - initWithFrame is the method to call when alloc/initing the object in code; initWithCoder is the init method called by the system if loading the object from a storyboard or xib.
To create one of your custom buttons in code, you alloc/init as you would any other object:
MyCustomButton* button = [[MyCustomButton alloc] initWithFrame:buttonFrame];
You wouldn't also alloc/init the superclass instance, this is done by the initWithFrame: method in the subclass when it calls [super initWithFrame:frame]. self refers to your custom subclass instance, but that includes all of the (public) properties and methods from it's superclass - unless you have implemented overrides in the subclass.
To use your subclassed button in a storyboard/xib, just drag out a regular button then set it's type to your custom button class in the Identity Inspector. The initWithCoder method is called automatically when the button is loaded from the storyboard/xib into a view.
update
From your comments, you seem to harbour a few confusions still, so here are some highly compressed de-obfuscating notes...
Keep away from subclassing UINavigationController unless you really know what you are doing. It's rarely necessary.
The buttons on a navController's interface are properties of it's contained viewControllers. Look up the navigationItem property of UIViewController (similarly - in the case of a UIToolbar - the View Controller has a toolbarItems property). This allows Navigation Controllers to be context-aware.
The 'viewDidLoad' in my example is assumed to be in a regular UIViewController. My example is also a category on the regular UIBUtton which has no formal relationship with UIBarButtonItem.
Try getting a UIButton category to work with a regular ViewController first before experimenting with UIBarButtonItem (which does not inherit from UIButton).
UIBarbuttonItem has no initWithFrame, because the thing that organises the bar (UINavigationBar or UIToolbar) - in this case a Navigation Controller - is responsible for it's ultimate size and positioning. The viewController governs the relative order of barButtonItems, and whether they appear on the left or the right, and the content and (some aspects of) it's appearance, but the rest is up to the NavController.
I'm using an NSCollectionView to display various objects. The whole things works rather well, except for one annoying thing. I cannot figure out how to access the various controls on the view used to represent each object in the collection.
Here's the setup:
I have dragged an NSCollectionView into my view in IB.
I made a custom subclass of NSCollectionViewItem. Mapped my class in IB.
I made a custom subclass of NSBox to act as the view for each object in the collection. Also mapped this class in IB and connected it to the view property of my NSCollectionViewItem subclass.
I made all the bindings in IB to display the correct information for each object.
The view:
The resulting collection view:
Reasoning that that my subclass of NSCollectionViewItem is basically a controller for each view in the collection, I made referencing outlets of the various controls in the view in my controller subclass:
#interface SourceCollectionViewItem : NSCollectionViewItem
#property (weak) IBOutlet NSTextField *nameTextField;
#property (weak) IBOutlet NSTextField *typeTextField;
#property (weak) IBOutlet RSLabelView *labelView;
#property (weak) IBOutlet NSButton *viewButton;
#end
When I inspect any instance of SourceCollectionViewItem in the debugger, all the properties show up as nil despite the fact that I can actually see them on my screen and that everything is displayed as it should be.
My setup was inspired by Apple's sample app IconCollection.
I am obviously missing something. What?
EDIT: I found various posts hinting at a similar issue:
CocoaBuilder.com and this question on SO.
EDIT: Just to be complete: this post deals with the subject as well and delivers a solution based on a combination of the options mentioned in the accepted answer.
Outlets are set during nib loading, and only the prototype item is loaded from nib and has its outlets assigned. All other ViewItems and their Views are cloned from the prototype, in that case outlets are just instance variables that are never initialized.
Here are the options I could come up with:
Override newItemForRepresentedObject: of collection view and reload nib instead of cloning the prototype. But this will probably hurt the performance greatly.
Override copyWithZone of collection view item and assign outlets manually using viewWithTag: to find them.
Give up and try to provide data via bindings only.
I found that overriding NSCollectionViewItem's -setRepresentedObject: could also be a good choice, as it is called on the new Item when all IBOutlet seem to be ready. After the call to super you can do whatever is needed:
- (void)setRepresentedObject:(id)representedObject
{
if (representedObject) {
[super setRepresentedObject:representedObject];
[self.anOutlet bind:#"property" toObject:self.representedObject withKeyPath:#"representeProperty" options:nil];
}
}
I used this method to bind a custom property of an interface object. The check is there to avoid useless calls, when the representedObject is not yet ready. The project uses a separate xib for the ViewItem, as explained in the links in the original edits.
Great question. Like #hamstergene suggests, you can use copyWithZone, it will be much more efficient compared to newItemForRepresentedObject. However viewWithTag is not always an option, first, because not everything can be tagged (easily), and, second, using tag for this purpose is a little wrong. Here's a cool approach with performance in mind, in Swift.
import AppKit
class MyViewController: NSCollectionItemView
{
// Here you are cloning the original item loaded from the storyboard, which has
// outlets available, but as you've seen the default implementation doesn't take
// care of them. Each view has a unique identifiers, which you can use to find it
// in sublayers. What's really cool about this, is that you don't need to assign
// any tags or do anything else while having advantage of better performance using
// cached nib object.
override func copyWithZone(zone: NSZone) -> AnyObject {
let copy: NSCollectionItemView = super.copyWithZone(zone) as! NSCollectionItemView
let oldView: RecordingView = self.view as! MyView
let newView: RecordingView = copy.view as! MyView
newView.foo = newView.viewWithIdentifier(oldView.foo.identifier!) as! NSTextfield
newView.bar = newView.viewWithIdentifier(oldView.bar.identifier!) as! NSImageView
return copy
}
}
#IBDesignable class MyView: View
{
// Custom collection view item view. Lets assume inside of it you have two subviews which you want
// to access in your code.
#IBOutlet weak var foo: NSTextfield!
#IBOutlet weak var bar: NSImageView!
}
extension NSView
{
// Similar to viewWithTag, finds views with the given identifier.
func viewWithIdentifier(identifier: String) -> NSView? {
for subview in self.subviews {
if subview.identifier == identifier {
return subview
} else if subview.subviews.count > 0, let subview: NSView = subview.viewWithIdentifier(identifier) {
return subview
}
}
return nil
}
}
I have a UIViewController with an xib and using Interface Builder I've added a child UIView.
Within the child UIView, when I click on an object within that view, I want to be able to alter the title of the whole window.
Now I'd normally do that setting
self.title = #"hi";
on the parent UIViewController. But is there any way I can access the parent title from within the child?
I've tried
self.superview.title = #"i";
self.parentViewController.title = #"hi";
but neither work.
Any help much appreciated
thanks
self.superview.title = #"i"; evaluates to an object of type UIView, and UIView has no title property. UIViewControllers have a parentViewController property but UIViews don't.
So the fundamental problem is that you're not properly separating your controller and your view classes. What you'd normally do is make the view you want to catch taps on a subclass of UIControl (which things like UIButton already are, but if it's a custom UIView subclass then you can just change it into a UIControl subclass since UIControl is itself a subclass of UIView), then in your controller add something like:
- (void)viewDidLoad
{
[super viewDidLoad];
// we'll want to know if the view we care about is tapped;
// we've probably set up an IBOutlet to it but any way of
// getting to it is fine
[interestingView
addTarget:self
action:#selector(viewTapped:)
forControlEvents:UIControlEventTouchDown];
// UIButtons use UIControlEventTouchUpInside rather than
// touch down if wired up in the interface builder. Pick
// one based on the sort of interaction you want
}
// so now this is exactly like an IBAction
- (void)viewTapped:(id)sender
{
self.title = #"My new title";
}
So you explicitly don't invest the view with any knowledge about its position within the view hierarchy or how your view controllers intend to act. You just tell it to give you a shout out if it receives a user interaction.
I have an UIButton "bn" and an UIActivityIndicator "ai" which is above the button (ai.center = bn.center).
As long as ai is visible and animating, I can't press the Button underneath ai's frame but out of the range I can.
Do I have to add GestureRecognition to ai or is there a smarter way to click on the "ai".
Kind regards. $h#rky
Can you simply set ai.userInteractionEnabled = NO;? I'm surprised it is enabled anyway, on an activity indicator - is this a standard component or have you made a subclass?
As an aside, it is usually poor UI design to have an interactive element that is covered by another view, particularly one which is used to indicate that something is "busy", but in your example of a clickable thumbnail image, it seems to make sense.
You need to override the UIView method
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
in the parent view. If the hit is within the button the you return the button, else you return nil. This is part of the the discussion on this method:
This method traverses the view hierarchy by sending the
pointInside:withEvent: message to each subview to determine which
subview should receive a touch event. If pointInside:withEvent:
returns YES, then the subview’s hierarchy is traversed; otherwise, its
branch of the view hierarchy is ignored. You rarely need to call this
method yourself, but you might override it to hide touch events from
subviews.
EDIT:
Say you have a UIView subclass which contains bn and ai, you can implement the method like this
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
if (CGRectContainsPoint(bn.frame, point)) {
return bn;
}
return nil;
}
that way your button will get the touch events (if they are within its frame) no matter if something is on top of it or not. You do not need to do anything else.
Use the following stuff:
First, create subclass for UIActivityIndicator with the following method override:
#interface MyActivityIndicator: UIActivityIndicator
#end
#implementation MyActivityIndicator
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
return NO;
}
#end
After that, use MyActivityIndicator everywhere in your project instead of UIActivityIndicator (in NIB file or in your code, depends where do you create it)
I have a Document based core data app. The main document window has a number of views, each controlled by its own custom NSViewController which are switched in as necessary. I want each of these view controllers to be able to drop down a custom modal sheet from the document window. However because the views are separate and not in the MyDocument nib I cannot link the view to the document window in IB. This means that when I call
[NSApp beginSheet: sheetWindow modalForWindow: mainWindow modalDelegate: self didEndSelector: #selector(didEndSheet:returnCode:contextInfo:) contextInfo: nil];
I’m supplying nil for mainWindow and the sheet therefore appears detached.
Any suggestions?
Many Thanks
You can use [[self view] window]
Indeed, it's self.view.window (Swift).
This may be nil in viewDidLoad() and viewWillAppear(), but is set properly by the time you get to viewDidAppear().
One issue with the other answers (i.e., just looking at self.view.window) is that they don't take into account the case that when a view is hidden, its window property will be nil. A view might be hidden for a lot of reasons (for example, it might be in one of the unselected views in a tab view).
The following (swift) extension will provide the windowController for a NSViewController by ascending the view controller hierarchy, from which the window property may then be examined:
public extension NSViewController {
/// Returns the window controller associated with this view controller
var windowController: NSWindowController? {
return ((self.isViewLoaded == false ? nil : self.view)?.window?.windowController)
?? self.parent?.windowController // fallback to the parent; hidden views like those in NSTabView don't have a window
}
}
If your controller can get access to the NSDocument subclass, you can use -windowForSheet
more about Tim Closs answer :
-(void)viewDidAppear
{
self.view.window.title = #"title-viewDidAppear"; //this only works when and after viewDidAppeer is called
}
-(void)viewWillDisappear
{
self.view.window.title = #"title-viewWillDisappear"; //this only works before and when viewWillDisappear is called
}