I've created a sub class of UIButton:
//
// DetailButton.h
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#interface MyDetailButton : UIButton {
NSObject *annotation;
}
#property (nonatomic, retain) NSObject *annotation;
#end
//
// DetailButton.m
//
#import "MyDetailButton.h"
#implementation MyDetailButton
#synthesize annotation;
#end
I figured that I can then create this object and set the annotation object by doing the following:
MyDetailButton* rightButton = [MyDetailButton buttonWithType:UIButtonTypeDetailDisclosure];
rightButton.annotation = localAnnotation;
localAnnotation is an NSObject but it is really an MKAnnotation. I can't see why this doesn't work but at runtime I get this error:
2010-05-27 10:37:29.214 DonorMapProto1[5241:207] *** -[UIButton annotation]: unrecognized selector sent to instance 0x445a190
2010-05-27 10:37:29.215 DonorMapProto1[5241:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIButton annotation]: unrecognized selector sent to instance 0x445a190'
'
I can't see why it's even looking at UIButton because I've subclassed that so it should be looking at the MyDetailButton class to set that annotation property. Have I missed something really obvious. It feels like it :)
Thanks in advance for any help you can provide
Ross
UIButton is a class cluster, which implies that Apple's implementation of buttonWithType: probably looks something like this:
+(id)buttonWithType:(UIButtonType)t {
switch (t) {
case UIButtonTypeDetailDisclosure:
return [[[PrivateDetailDisclosureButtonClass alloc] init] autorelease];
case ...
}
}
So when you call [MyDetailButton buttonWithType:UIButtonTypeDetailDisclosure]; you don't get an instance of MyDetailButton, you get an instance of PrivateDetailDisclosureButtonClass (or whatever Apple actually calls it).
Note, however, that you can get buttonWithType to instantiate a subclass if you call it with UIButtonTypeCustom (At least in the simulator running v3.0):
// LGButton is a straightforward subclass of UIButton
LGButton *testBtn = [LGButton buttonWithType:UIButtonTypeCustom];
LGButton *testBtn2 = [LGButton buttonWithType:UIButtonTypeDetailDisclosure];
NSLog(#"testBtn: %#, testBtn2: %#", [testBtn class], [testBtn2 class]);
// Output: testBtn: LGButton, testBtn2: UIButton
I made the same attempt as original poster but it seems that subclassing UIButton to do something like this is hard.
What I did, which is a hack - but works for me now, is add a UITextField as subview of the UIButton. The UITextField has no frame and is hidden, but I can freely store text strings in the textfield's text property. Which is what I wanted to do...
UITextField* tf = [[UITextField alloc] init];
tf.text = #"the text that I wanna store";
tf.hidden = YES;
tf.tag = TAGOFBUTTONSUBTEXTFIELD;
[previouslyCreatedButton addSubview:tf];
[tf release];
I defined TAGOFBUTTONSUBTEXTFIELD as 99 somewhere. Global. It's ugly but...
Then later, to get that text string use something like this:
+(NSString*)getStoredStringFromButton:(UIButton*)button {
UITextField* tf = (UITextField*)[button viewWithTag:TAGOFBUTTONSUBTEXTFIELD];
return tf.text;
}
So this assumes that no one else tries to add a subview with tag 99 to the button.
Lol :-)
That exception is because the actual button that you are trying to get the annotation from is not of class MyDetailButton, it is a UIButton. Verify that you set the class in IB for that particular button. Select the button in IB and press ⌘4 to see its identity, change the Class Identity to MyDetailButton.
Just making a subclass isn't enough; the subclass does not take the place of its superclass. The same way not all UIControls, not all UIViews, not all UIResponders, and not all NSObjects have the behavior of UIButton, not all UIButtons have the behavior of your custom subclass.
What you need is an instance of your subclass. What you have is an instance of UIButton.
The solution is to make that instance an instance of your subclass instead. If you created the button in Interface Builder, select the button and press ⌘6, then change the instance's Custom Class there. If you're creating the button in code, send your alloc message to your custom subclass, not directly to UIButton.
Related
I've been able to programmatically create a NSPopupButton and add it to my window, and I can add items to the list from the same method, but I'd like to figure out how I can add items to it from another method.
Here's what I have so far that works:
// in my .h file:
#interface AVRecorderDocument : NSDocument
{
#private
NSPopUpButton *button;
}
#property (assign) IBOutlet NSWindow *mainWindow;
// in my .m file:
#implementation AVRecorderDocument
#synthesize mainWindow;
- (void)windowControllerDidLoadNib:(NSWindowController *) aController
{
NSView *superview = [mainWindow contentView];
NSRect frame = NSMakeRect(10,10,149,22);
NSPopUpButton *button = [[NSPopUpButton alloc] initWithFrame:frame];
[superview addSubview:button];
[button release];
}
- (void)refreshDevices
{
// I'd like to add items to my popupbutton here:
// [button addItemWithTitle: #"Item 1"];
}
#end
Up in refreshDevices I don't get a compiler error, just nothing gets added to the popupbutton. The method refreshDevices is called from -(id)init. I've also tried putting the code that is inside the windowControllerDidLoadNib at the top of my init section, but it won't even create the popupbutton there.
There are a two problems with your code:
Inside windowControllerDidLoadNib:
You don't assign the newly created button to your ivar but only to a function local variable (with the same name as your ivar).
Why nothing happens inside refreshDevices
init is called before windowControllerDidLoadNib:, so your ivar is nil (and because of 1.). Sending messages to nil does nothing.
Solution:
Remove NSPopUpButton * from windowControllerDidLoadNib: so you assign the new button to your ivar and not to some function local variable.
Call refreshDevices at the end of windowControllerDidLoadNib: or at some point you know windowControllerDidLoadNib: has been called and your button is not nil.
Edit:
You should keep in mind that the moment you remove the button from the superview it is probably deallocated because you release it after creation.
The moment it is deallocated your button ivar points to an invalid/deallocated object which leads to undefined behaviour when used in this state.
I'd advise to release the button inside dealloc so you can be sure to have a valid object throughout the whole lifetime of your document object.
But nonetheless I don't know your exact use case which might require this design.
I'm trying to break some of my "super objects" into more manageable classes that have single (or at least limited) responsibility.
One problem I've just run into is making an object of a specific instance of a UIBarButtonItem. In the class it is in now I first define a UIButton, and then all of the images that act as icons for that button as subviews (for instance the button represents access/control to a device, and I use the button image to show the current signal strength of that device). Also that button is listening for NSNotifications from the device object to represent the signal strength changing, or if the device disconnects. And pressing the button sends a message to the device to disconnect. All of this code works perfectly fine now as a property of the RootViewController. However, I want to pull it out into its own class as the button is shared by several classes, and it just clutters up the controller with unnecessary methods.
I tried making an separate class with an init like below. However, this doesn't work as the self used for the button isn't the same self that is ultimately created by [UIBarButtonItem alloc] and when either the NSNotification or the button press try to send a message to the selector of "self", that object has already been dealloced. The problem is, I'm not sure how to create a object (as defined by the class) that is just an instance of another class, as opposed to a property of an object (as it currently is for the RootViewController).
Edit and additional explanation of my problem
MyClass is currently subclass of UIBarButtonItem. However, I'm not trying to use it like this: [[MyClass alloc] initWithCustomView:]. I want [MyClass alloc] init] by itself to completely create the custom view - in other words the whole point of this class is to completely contain all that is necessary for this button to create itself, manage its subviews, and take the appropriate action when it is pressed. (I could easily make MyClass an NSObject with a public method like [MyClass setupButton] and a public property of type UIBarButtonItem. However, I think that looks wrong because then the class is only there to create the button, but it is not the button itself.)
#interface MyClass : UIBarButtonItem
#end
#implementation MyClass
- (id)init {
if (self = [super init]) {
UIImage *defaultButton = [[UIImage imageNamed:#"...
UIImage *defaultButtonPressed = [[UIImage imageNamed:#"....
UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 40, 30)];
[button setBackgroundImage:defaultButton forState:UIControlStateNormal];
[button setBackgroundImage:defaultButtonPressed forState:UIControlStateHighlighted];
[button addTarget:self action:#selector(deviceButtonPressed) forControlEvents:UIControlEventTouchUpInside];
//Then several UIImageViews that are added as subviews of the button, initially hidden
//Then set up the NSNotification listener
//Finally
self = [[UIBarButtonItem alloc] initWithCustomView:button];
}
return self;
}
//Then several functions to handle hiding and unhiding the subviews depending on the received device notifications, and a function to handle the button press and sending the message back to the device.
This is not how initialization works in Cocoa. Please read "Initialization" in the Cocoa Core Competencies guide.
Your object has already been allocated when this init method is run. You should not be reassigning the self pointer to another allocation.
Your class should first call its superclass's designated initializer self = [super initWithWhatever:obj];, then set up its own properties.
It seems to me that you want to extend UIBarButtonItem, not create an instance of it in your init method. Try changing your class declaration (in your class's .h file) from this:
#interface MyClass : NSObject
to this:
#interface MyClass : UIBarButtonItem
Then just return self in your init method. Setting self to a value is usually a bad idea.
If you're unsure about what's going on here, you're creating a subclass of UIBarButtonItem. This lets your subclass extend the superclass's functionality. If you're confused, you should take a look at subclassing/class inheritance in object-oriented languages to understand what's going on. This guide documents how classes work in Objective-C.
I saw this answer of how to create a placeholder for UITextView.
I took the following steps:
Add to the .h class the declaration:
#interface AdjustPhotoViewController : UIViewController<UITextViewDelegate>
Added the method:
- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
NSLog(#"%d",[textView tag]);
if ([textView tag]==1){
campaignTitle.text = #"";
}else{
campaignDescription.text = #"";
}
return YES;
}
But I don't see that the method is being invoked!
What am I missing?
textView is already delegated via the storyboard to the view
SOLVED:
The problem was that it wasn't delegated. Although I was using storyboard - it was only an outlet, not a delegate.
Remember that if you are using storyboard, you need to delegate also from the text view to the orange button of the view! not only the other way
What am I missing?
Actually setting the delegate.
textView.delegate = self;
Merely conforming to a protocol won't magically make your object into the delegate of an arbitrary object; that's just a formal thing, and anyways, how on Earth would the UITextField know which particular instance of the class it has to assign its delegate?
I have a UIView subclass that I assign to a text field as follows:
self.textField.inputView = [[HexKeyboard alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
and this works (i.e., the keyboard comes up). However, how should the HexKeyboard instance know about the textField?
[Of course I can add a property to the HexKeyboard to achieve this (and call it delegate), but I figure there's a built-in mechanism for this...]
You don't really need a complex delegate pattern for this. Just create a property of type UITextField on your HexKeyboard class, and make it an unsafe_unretained reference so you don't get a retain loop:
#interface HexKeyboard
#property (nonatomic, unsafe_unretained) UITextField *textField;
#end
Then set it when you set your inputView:
self.textField.inputView = [[HexKeyboard alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
self.textField.inputView.textField = self.textField;
There seems to be no built-in mechanism for this, as the other answerers have pointed out. As Nick says, you don't need a complex delegate pattern for this. Or rather, you use the delegate pattern, but you get the delegate class for free. In this case it's the UITextInput protocol.
So your keyboard probably looks like this (and has a NIB)
#interface ViewController : UIViewController
// use assign if < iOS 5
#property (nonatomic, weak) IBOutlet id <UITextInput> *delegate;
#end
When you create the keyboard controller, you assign the UITextInput conformer to it, so something like this:
- (void)viewDidLoad
{
[super viewDidLoad];
HexKeyboardController *keyboardController = [[HexKeyboardController alloc] initWithNibName:#"HexKeyboardController" bundle:nil];
self.textField.inputView = keyboardController.view;
keyboardController.delegate = self.textField;
}
However, I thought, there MUST be a way to define this keyboard just once and get the keyboard to "automatically know" who the UITextInput object that summoned it is. But I've looked around to no avail... you cannot figure out who the firstResponder is unless you troll the view hierarchy yourself or retain your delegates in a list (which would cause a retain loop). Plus, this isn't so bad because the HexKeyboardController will unload, too, when the textField is dealloced.
I dont believe there is a built in mechanism for this, you probably want the a delegate in the hex keyboard that will receive the "keystrokes" from it and then append it to the textfield, or whatever it is you need to do..
I'm having trouble connecting the dots between code and .xib files.
If I want to add a series of UIButtons programmatically to my view controller, how would I go about doing this from a separate class?
For instance, if I have MainViewController.m, which is set as the root view controller in Xcode, how can I add a UIButton to that view controller from SecondViewController.m? Is this even possible?
I would essentially like to place all of my "user interface" code in a separate class.
Thanks
To do this, create a UIButton *myButton programmatically and then call [mainViewController addSubview:myButton];. This may mean you need to store a MainViewController * property in your SecondViewController class.
Important methods and properties for a UIButton instance (essentially, just take a look at the documentation, but here's a minimal set of stuff to get you started):
+[UIButton buttonWithType:buttonType] - Make sure if you're doing anything remotely custom to use UIButtonTypeCustom here (it doesn't give you any default background images or otherwise to have to nil out)
setFrame: - Position the button relative to its container and set the size, for usability reasons the width and height should be at least 44 pixels (as mentioned here).
setTitle:forState: - UIControlStateNormal will act as the default properties for other states too, so you may only need to set the text here
setBackgroundImage:forState: - use UIControlStateNormal and UIControlStateHighlighted/UIControlStateSelected primarily, UIControlStateDisabled if you wish to show it grayed out or inaccessible at any point.
setImage:forState: - Use for an icon next to the button text (like an arrow pointing down for Save or up for Load, etc)
setEnabled:, setHidden:, setSelected: - Transition between different button states. setHighlighted: happens automatically when you tap the button.
addTarget:self action:#selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside - TouchUpInside is almost always what you want for a simple button press, I'm using a method named buttonClicked: here to handle my button press.
Oh, and if you use [[UIButton alloc] initWith...] don't forget to [myButton release] once it's added to the mainViewController :)
use this
#import "MainViewController.h"
#interface SecondViewController
{
MainViewController *mainView;
}
#property(nonatomic, retain) MainViewController *mainView;
-(void)addButtons;
In your implementation
#synthesize mainView;
-(void)addButtons
{
UIButton *add = [UIButton alloc] init];
//do necessary stuff on button here
[self.mainView addSubview:add];
[add release];
}
In your MainViewcontroller.m
#import "SecondViewController.h"
-(void)viewDidLoad
{
[self superViewDidLoad];
SecondViewController *second = [SecondViewController alloc] init];
second.mainView = self;
[second addButton];
[second release];
}