It must be one of those things where there's a tiny mistake i've missed, or something, but i can't seem to figure it out.
Viewcontroller.h
#import "RGBEditView.h"
#interface ColorPickerView : UIViewController {
RGBEditView *rgbEditView;
}
-(void)showRGBEditor;
.m
-(void)showRGBEditor {
rgbEditView = [[RGBEditView alloc] initWithFrame:CGRectMake(0, 0, 280, 46) H:h S:s B:b];
}
It's this line above, the initwithframe line, that gives the error 'Incompatible Objective-C types assigning '*', expected '*'
RGBEditView.h
#interface RGBEditView : UIView {
}
-(RGBEditView *)initWithFrame:(CGRect)frame H:(float)hue S:(float)saturation B:(float)brightness;
RGBEditView.m
-(RGBEditView *)initWithFrame:(CGRect)frame H:(float)hue S:(float)saturation B:(float)brightness {
[super initWithFrame:frame];
return self;
}
Can anybody see my problem? I'm very confused about this.
EDIT:
The problem lies in that I have another class which also uses initWithFrame:H:S:B:, so the only way to fix this is to change on of them to something a bit different, but this seems like an awkward work around. Any other solutions?
the methods init and methods that start with initWith should return type id.
what typically happens is that you have 2 classes with the same method name (initializer in this case), but differ in their return types:
RGBEditView
-(RGBEditView *)initWithFrame:(CGRect)frame H:(float)h S:(float)s B:(float)b;
HSBEditView
-(HSBEditView *)initWithFrame:(CGRect)frame H:(float)h S:(float)s B:(float)b;
alloc returns id - the compiler warns you because it sees an expression which resembles type assignment used in the following example:
RGBEditView * rgb = /* ... */;
HSBEditView * hsb = nil;
hsb = rgb // << compiler: "hey - you don't want to do that unless
// RGBEditView were a subclass of
// HSBEditView... but it's not!"
you correct this by returning id from your initializers, like this:
-(id)initWithFrame:(CGRect)frame H:(float)h S:(float)s B:(float)b;
you return id to avoid clashes like this, and because the compiler doesn't know what type is returned via alloc, so every subclass declaration would have to return a different type - which would only lead to more problems.
the exception to this is to use well qualified names - and is typically seen in convenience constructors:
+ (HSBEditView *)newHSBEditViewWithFrame:(CGRect)frame
H:(float)h S:(float)s B:(float)b;
in RGBEditView.m try
self = [super initWithFrame:frame];
return self;
initWithFrame should be
-(RGBEditView *)initWithFrame:(CGRect)frame H:(float)hue S:(float)saturation B:(float)brightness {
self = [super initWithFrame:frame];
return self;
}
Related
EDIT: I apologize for wasting time, the erorr had nothing to do with what I'm taking about but rather some logic in my code that made me believe this was the cause. I'm awarding Kevin with the correct answer since using his idea to pass the whole AuthorSelectionView, and his note on correcting the NSNumer mistake. Sorry about that.
I've been trying to figure this out for hours, and even left it alone for a day, and still can not figure it out...
My situation is as follows:
I've created a custom class that implements 'UIView' and made this class into a protocol as follows:
custom UIView h file
#protocol AuthorSelectionViewDelegate <NSObject>
-(void)AuthorSelected:(NSNumber *)sender;
#end
#import <UIKit/UIKit.h>
#interface AuthorSelectionView : UIView
#property (nonatomic,assign) id<AuthorSelectionViewDelegate> delegate;
#property (strong,retain) NSNumber *authorID;
- (id)initWithFrame:(CGRect)frame withImage:(UIImage *)img withLabel:(NSString *)lbl withID:(int)authorID ;
#end
the implementation...
- (id)initWithFrame:(CGRect)frame withImage:(UIImage *)img withLabel:(NSString *)lbl withID:(int)authorID
{
self = [super initWithFrame:frame];
if (self) {
self.authorID = [[NSNumber alloc] initWithInt:authorID]; //used to distinguish multiple instances of this class in a view.
...
UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, FRAMEWIDTH, FRAMEHEIGHT)];
[button addTarget:self action:#selector(CUSTOMBUTTONCLICK) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:button];
}
return self;
}
- (void) CUSTOMBUTTONCLICK
{
[self.delegate performSelector:#selector(AuthorSelected:) withObject:self.authorID];
}
Now the method in my delegate object gets called just fine, but my major problem here is that something is going on with the object being pass through when i have multiple instances of the AuthorSelected class alloc'd.. (the NSNumber authorID). I'm getting some weird behavior with it. It seems almost random with the value being passed, but i'm detecting some pattern where the value passed through is coming up late..
thats confusing so ill try to explain:
I create two instances of the AuthorSelected view, one with authorID=1 and the other with authorID=2.
On the first press, lets say i press the first button, i'll get 1 as expected.
On the second press, if I press the 1st custom button, i'll get '1', but if i press the second i'll still get 1.
On the third go, either button will give me back '2'
I feel like this is some issue with pointers since that has always been a weak point for me, but any help would be greatly appreciated as I can not seem to figure this one out.
Thank you!
EDIT:
as requested here is how I create the AuthorSelectionView Objects...
AuthorSelectionView * asView01 = [[AuthorSelectionView alloc]
initWithFrame:CGRectMake(0, 0, FRAMEWIDTH, FRAMEHEIGHT)
withImage:userPic1
withLabel:randomUserName
withID:1];
asView01.delegate = self;
AuthorSelectionView * asView02 = [[AuthorSelectionView alloc]
initWithFrame:CGRectMake(0, 0, FRAMEWIDTH, FRAMEHEIGHT)
withImage:userPic2
withLabel:randomUserName2
withID:2];
asView02.delegate = self;
A detail that may be important:
As soon as i click on one of these custom views, my code is set to (for now) call the method that runs the above AuthorSelectionView alloc code, so that i can refresh the screen with the same layout, but with different userpic/userName. This is poor design, I know, but for now I just want the basic features to work, and will then worry about redrawing. I metion this tidbit, becuase I understand that objective-c 'layers' veiws on top of eachother like paint on a canvas, and had a thought that maybe when I click what I think may be my 2nd button, its really 'clicking' the layer beneath and pulling incorrect info.
Your description of the problem is a bit confusing, but this line in your init is very clearly wrong:
self.authorID = [self.authorID initWithInt:authorID];
In -init, your property self.authorID defaults to nil, so the expression [self.authorID initWithInt:authorID] is equivalent to [nil initWithInt:authorID], which evaluates back to nil. So you should actually be seeing nil in your action. You probably meant to say self.authorID = [NSNumber numberWithInt:authorID]
You're missing the alloc message, so this message:
self.authorID = [self.authorID initWithInt:authorID];
Is sent to a nil target, because self.authorID hasn't been allocated yet.
So first allocate it, then use the init method, or mix these two messages. A faster syntax allows to do it this way:
self.authorID= #(authorID);
EDIT
I don't see where you initialize the delegate, that method shouldn't even be called if you haven't initialized it. Show the code where you create the AuthorSelectionView objects and set the delegates.
instead of :
self.authorID = [self.authorID initWithInt:authorID];
put :
self.authorID = [NSNumber numberWithInt:authorID];
or
self.authorID = [[NSNumber alloc] initWithInt:authorID];
EDIT :
Don't you have errors or warnings in your code ? I can't see you returning self object in the init method ("return self;")
I have a main game class which renders the game using Open GL. Now I thought I could inherit from this class and then just call [super init] in its init method to get a copy of it. The plan was to make some modifications in the copy but as it seems this doesn't work.
The following is the header file of my class:
#import "GameView.h"
#interface CloneView : GameView {
}
-(id)initWithFrame:(CGRect)frame;
#end
And this is the Clone view class:
#implementation CloneView
-(id)initWithFrame:(CGRect)frame{
return [super initWithFrame:frame];
}
#end
If I set a break point in the init method in the GameView class it stops there. Thing is: my clone view doesn't get rendered, the screen stays black.
What am I missing? Thanks for your help!
Edit
Just for the record: I tried without implementing initFrame and got the same result. (as expected as the initFrame as above isn't doing anything apart from calling super)
Edit 2
I'm adding my clone to another view so I'm creating two Eagle contexts. Could that be the reason why it doesn't work?
If you are not adding anything in the init function of CloneView than you don't even have to rewrite it. You can just have your class inherit from GameView and it automatically copies it's init function.
This is from the apple docs
You should assign self to the value returned by the initializer because the initializer could return an object different from the one returned by the original receiver.
So Try doing this
-(id)initWithFrame:(CGRect)frame{
if(self = [super initWithFrame:frame] ) {
//Do whatever you need to do here.
}
return self;
}
This should fix your issue if you need to do something in your init method. Otherwise you can skip the init method altogether.
try doing this it may work..
return(self=[super initWithFrame:frame])
which ensures the super class method is copied properly to the current method
TNQ
I finally located the problem:
I needed to write a second init method. The problem was that the following code was being executed twice:
CAEAGLLayer *eaglLayer = (CAEAGLLayer *)[super layer];
[eaglLayer setOpaque:YES];
m_context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];
if (!m_context || ![EAGLContext setCurrentContext:m_context]) {
printf("FAIL \n");
[self release];
return nil;
}
[Textures loadTexture];
if ([self createFramebuffer]) {
[self draw];
}
This code was in the initFrame method of the game class. I made a second init method that does not execute this code. Instead, this code is executed in the parent view class of the clone. Now it works, YAY!!
Thanks for trying to help me!
Can someone help me understanding as why do we call an initialization method on super first before initializing. I came across a piece of code in a subclass of UIView and wanted to know that here myMethod is always getting called that means I am not getting the frame set in UIView, then why are we doing this and using an if condition.
self = [super initWithFrame:CGRectMake(0, 0, 20, 100)];
if(self != nil) {
[self myMethod:data];
self.backgroundColor = [UIColor clearColor];
}
return self;
Let's say I have a UIView subclass called SpinningView. The code to create spinningView would look like this:
SpinningView *spinner = [[SpinningView alloc] initWithFrame:CGRectMake(0.0, 0.0, 20.0, 20.0)]
Now let's take a look at the implementation of SpinningView's -initWithFrame: method
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self)
{
self.backgroundColor = [UIColor clearColor];
}
return self;
}
The first line is simple assignment. We're assigning ourselves to the result of UIView's implementation of -initWithFrame:
We use the if statement to see if self is even valid. If it's not we just return it. If it is, we configure it.
This is simply calling the constructor of the super class (in this case UIView).
You need to call UIView's constructor to make sure that all the variables you don't see from your subclass is set up properly, and that's what you do with [super init] (or in this case initWithFrame:).
There are a few other reasons why it looks like this.
First of all [super init] might return nil. Perhaps something went wrong initializing things in the code of the superclass. The check for self != nil makes sure you don't use the object when something is already wrong with the object. It might even have been released by the super constructor.
In other cases the super constructor might actually return a different object altogether. Examples of this happening is with class clusters or when you implement a singleton.
To summarize:
Always call the designated constructor (i.e. init-method).
Always use the standard construct of if ((self = [super init])) { /* own init */ } return self;
Sometimes it looks different, but only for special reasons. If in doubt, always use (2).
Apple's documentation has a lot more info on this is you're interested.
Also, when overriding constructors like this, remember that there might be more than one constructor. For instance, if you add the view using Interface Builder, that view will be initialized using "initWithCoder:" instead. All constructors begin with "init" though.
I have 3 classes of objects. All 3 classes share some properties in common, as color, text, etc.
For example, I can have this
Class1 *objectA = [[Class1 alloc] init];
objectA.myColor = [UIColor redColor];
Class2 *objectB = [[Class2 alloc] init];
objectA.myColor = [UIColor redColor];
Class3 *objectC = [[Class3 alloc] init];
objectA.myColor = [UIColor redColor];
... etc.
Now I need, for example, to create a method that can change the color of a given object, whatever class it represents.
A typical method would be
- (void) changeColor:(Class1*) myOBJ toColor:(UIColor*)myColor {
myOBJ.color = myColor;
}
when in fact I need this
- (void) changeColor:(???) myOBJ toColor:(UIColor*)myColor {
myOBJ.color = myColor;
}
// what to put on ??? to make it generic? Is this a "whatever" kind?
thanks
EDIT
the problem of using this approach
- (void) changeColor:(id)myOBJ toColor:(UIColor*)myColor {
if ([myOBJ respondsToSelector:#selector(setColor:)]) {
myOBJ.color = myColor;
}
}
is this. Imagine I want to set the frame of the object.
Then I will have to have this:
- (void) changeColor:(id)myOBJ newFrame:(CGRect)myFrame {
if ([umID isKindOfClass:[Class1 class]]) {
Class1 *oneObj = (Class1 *)myObj;
oneObj.frame = myFrame;
}
if ([umID isKindOfClass:[Class2 class]])
Class2 *oneObj = (Class2 *)myObj;
oneObj.frame = myFrame;
}
if ([umID isKindOfClass:[Class3 class]])
Class3 *oneObj = (Class3 *)myObj;
oneObj.frame = myFrame;
}
}
in other words, I will have to repeat the same stuff 3 times... right?
in other words, the problem is not solved as this is the same of having 3 methods, one for each class.
Maybe you can use protocols? Make Class1, Class2 and Class3 conform to a protocol with a property myColor. Then you could have a method like this (assuming your classes are of type UIView and your protocol is called ColorProtocol):
- (void) changeColor:(UIView<ColorProtocol>*) myOBJ toColor:(UIColor*)myColor {
myOBJ.color = myColor;
myOBJ.frame = ...;
}
Here is what your protocol definition could look like:
#protocol ColorProtocol
#property (nonatomic, retain) UIColor *myColor;
#end
Change your class definition files (.h) as follows to specify that you will conform to the protocol:
interface Class1 : UIView <ColorProtocol> {...}
In the implementation files (.m) you must simply synthesize the myColor property to conform to the ColorProtocol:
#synthesize myColor;
If your classes are very similar, using inheritance might be even simpler though. Check out Philip Regan's answer.
You have a couple options. The simplest, and "most dangerous" approach is to use a type id. This will let you pass in any object, but you'll want to test that it actually has a color property before you try and set it.
- (void) changeColor:(id)myOBJ toColor:(UIColor*)myColor {
if ([myOBJ respondsToSelector:#selector(setColor:)]) {
myOBJ.color = myColor;
}
}
(That said, with the responds to selector check, this approach isn't all that dangerous, and it's much more flexible than the next idea.)
Another approach is to have all your objects inherit from a shared base class that has a color property. Then your parameter type would be the base class. This approach could be considered "safer" as the compiler would check that you're passing in the correct type of object. This approach also requires considerably more code.
If you want to use the first approach, but set something other than color, adjust the respondsToSelector: call appropriately.
- (void) changeFrame:(id)myOBJ newFrame:(CGRect)myFrame {
if ([myOBJ respondsToSelector:#selector(setFrame:)]) {
myOBJ.frame = myFrame;
}
}
In general, if you want to know if an object supports propertyX, use [myOBJ respondsToSelector:#selector(setPropertyX:)]. If the passed in object is declared as id, you can then call [myOBJ setPropertyX:newPropertyValue] or myObj.propertyX = newPropertyValue.
If you have multiple classes that share characteristics, then, if at all possible, I suggest refactoring the class structure so that those characteristics are contained in an umbrella parent class, we'll call it ClassZ. ClassZ's subclasses can override things as needed. Otherwise, let the method in the parent class handle it for you. Then, your method turns back into this...
- (void) changeColor:(ClassZ *) myOBJ toColor:(UIColor*)myColor {
myOBJ.color = myColor; // note, myObj is ClassZ, not the subclasses.
}
Otherwise, you are stuck with id and testing the individual classes.
use [object setFrame:newFrame]; instead of object.frame = newFrame;
and instead of oldFrame = object.frame; use oldFrame = [object frame];
??? will be 'id'.
I've got a problem (in Objective-C/iPhone dev) since more than one week, so I'd be really grateful if someone can help me out.
When I instantiate an object from a class that I've written, it returns me nil, but when I launch the debug mode I actually see in the init method that the attributes of self are correctly initialized and it seems like it doesn't execute the return self instruction.
EDIT:
Thanks for your answers Here is the init code
-(id)initWithDate:(NSString *)aDate
type:(NSString *)aType
amount:(NSString *)anAmount
currency:(NSString *)aCurrency
merchantName:(NSString *)aMerchant
status:(NSString *)aStatus
{
if (!(self = [super init])) return nil;
self->date=aDate;
self->type=aType;
self->amount=anAmount;
self->currency=aCurrency;
self->merchantName=aMerchant;
self->status=aStatus;
return self;
}
Don't use self->instanceVariable.
Just use instanceVariable.
I'd put your code inside the following
if (self = [super init]) {
// Custom initialization
}
return self;
rather than the if (!(self... return nil you have used. But that's just a habit.
I would also avoid the C++ style '->' assignments and instead use self.currency=aCurrency; (or [self setCurrency:aCurrency]; which is closer to the c++ calls I guess) assuming these are declared as #property or have getters and setters.
I'm sure one of those will get you going!
You should write
self.date = aDate;
// etc....
if date etc. is declared as a #property in the #interface, or if it's just a class instance variable, use
date = aDate;
// etc...
Also, if the strings are not declared as #property with retain or copy modifiers, you'll need to manually retain them thus:
date = [aDate retain];