Get Object by name

[icelandic]

I'm trying to change images in an app, but I want the iPhone to build the name of the object to change and then change it. Here's what I currently have but want to change...

.h file

PHP Code:

@interface implementation : NSObject <UIAlertViewDelegate>{
...
    IBOutlet UIImageView *q0;
    IBOutlet UIImageView *q1;
    IBOutlet UIImageView *q2;
    IBOutlet UIImageView *q3;
    IBOutlet UIImageView *q4;
    IBOutlet UIImageView *q5;
    IBOutlet UIImageView *q6;
    IBOutlet UIImageView *q7;
    IBOutlet UIImageView *q8;
    IBOutlet UIImageView *q9;

...
}

@property (nonatomic, retain) IBOutlet UIImageView *q0;
@property (nonatomic, retain) IBOutlet UIImageView *q1;
@property (nonatomic, retain) IBOutlet UIImageView *q2;
@property (nonatomic, retain) IBOutlet UIImageView *q3;
@property (nonatomic, retain) IBOutlet UIImageView *q4;
@property (nonatomic, retain) IBOutlet UIImageView *q5;
@property (nonatomic, retain) IBOutlet UIImageView *q6;
@property (nonatomic, retain) IBOutlet UIImageView *q7;
@property (nonatomic, retain) IBOutlet UIImageView *q8;
@property (nonatomic, retain) IBOutlet UIImageView *q9;

...
- (void) changeProgressionImages:(BOOL)correct;
...

@end 


.m file

PHP Code:

static NSString *correctAnswerImage = @"fffl_correct.png";
static NSString *wrongAnswerImage = @"fffl_wrong.png";
static NSString *currentAnswerImage = @"fffl_current.png";

@implementation implementation

@synthesize q0;
@synthesize q1;
@synthesize q2;
@synthesize q3;
@synthesize q4;
@synthesize q5;
@synthesize q6;
@synthesize q7;
@synthesize q8;
@synthesize q9;

int currentQuestionNumber = 0;
...

-(void) changeProgressionImages:(BOOL) correct    
{    
    NSString *imageLocation;
    
    if( correct )
        imageLocation = correctAnswerImage;
    else
        imageLocation = wrongAnswerImage;

    if( currentQuestionNumber == 0 )
    {
        q0.image = [UIImage imageNamed: imageLocation];
        q1.image = [UIImage imageNamed: currentAnswerImage]; 
    }
    else if( currentQuestionNumber == 1 )
    {
        q1.image = [UIImage imageNamed: imageLocation];
        q2.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 2 )
    {
        q2.image = [UIImage imageNamed: imageLocation];
        q3.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 3 )
    {
        q3.image = [UIImage imageNamed: imageLocation];
        q4.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 4 )
    {
        q4.image = [UIImage imageNamed: imageLocation];
        q5.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 5 )
    {
        q5.image = [UIImage imageNamed: imageLocation];
        q6.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 6 )
    {
        q6.image = [UIImage imageNamed: imageLocation];
        q7.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 7 )
    {
        q7.image = [UIImage imageNamed: imageLocation];
        q8.image = [UIImage imageNamed: currentAnswerImage];
    }
    else if( currentQuestionNumber == 8 )
    {
        q8.image = [UIImage imageNamed: imageLocation];
        q9.image = [UIImage imageNamed: currentAnswerImage];
    }
    else
    {
        q9.image = [UIImage imageNamed: imageLocation];
    }
}
...
@end 


Instead of having all that code in the changeProgressionImages method, I would like to something like this:

PHP Code:

//Incremented when question number changes
int currentQuestionNumber = 0;

...

-(void) changeProgressionImages:(BOOL) correct    
{    
    NSString *imageLocation;
    
    if( correct )
        imageLocation = correctAnswerImage;
    else
        imageLocation = wrongAnswerImage;

    NSString *gradedImageName = [NSString stringWithFormat: @"q%d", currentQuestionNumber];
    NSString *currentImageName = [NSString stringWithFormat: @"q%d", currentQuestionNumber+1];

//I know this is a javascript like reference
    getObjectByName( gradedImageName ).image = [UIImage imageNamed: imageLocation];

    getObjectByName( currentImageName ).image = [UIImage imageNamed: currentAnswerImage];

} 


I'm wondering if it this is possible.

[smasher]

It's possible, but it's not what you want here - you should use an array instead. You can add all of your object to an NSArray (or NSMutableArray if you need to modify the list) and access them like this:

//add imageViews to the array - do this once
NSArray *imageViews = [[NSArray alloc] initWithObjects: q0, q1, q2, q3, q4, q5, q6, q7, q8, q9, nil];

//pull imageviews from the array
UIImageview *gradedImage = [imageViews objectAtIndex:currentQuestionNumber];
gradedImage.image = [imageViews imageNamed: imageLocation];

UIImageview *currrentImage = [myArray objectAtIndex:currentQuestionNumber+1];
currentImage.image = [UIImage imageNamed: currentAnswerImage];

[icelandic]

Originally Posted by smasher

It's possible, but it's not what you want here - you should use an array instead. You can add all of your object to an NSArray (or NSMutableArray if you need to modify the list) and access them like this:

//add imageViews to the array - do this once
NSArray *imageViews = [[NSArray alloc] initWithObjects: q0, q1, q2, q3, q4, q5, q6, q7, q8, q9, nil];

//pull imageviews from the array
UIImageview *gradedImage = [imageViews objectAtIndex:currentQuestionNumber];
gradedImage.image = [imageViews imageNamed: imageLocation];

UIImageview *currrentImage = [myArray objectAtIndex:currentQuestionNumber+1];
currentImage.image = [UIImage imageNamed: currentAnswerImage];

I had to tweek the code a little but it's better than I got:

PHP Code:

    //add imageViews to the array - do this once
    NSArray *imageViews = [[NSArray alloc] initWithObjects: q0, q1, q2, q3, q4, q5, q6, q7, q8, q9, nil];
    
    //pull imageviews from the array
    UIImageView *gradedImage = [imageViews objectAtIndex:currentQuestionNumber];
    gradedImage.image = [UIImage imageNamed: imageLocation];
    
    UIImageView *currrentImage = [imageViews objectAtIndex:currentQuestionNumber+1];
    currrentImage.image = [UIImage imageNamed: currentAnswerImage]; 


I think I can solve this problem fully if I knew how to get the object id by only knowing the object name as a string. Is that possible?

[smasher]

Originally Posted by icelandic

I had to tweak the code a little but it's better than I got:

I think I can solve this problem fully if I knew how to get the object id by only knowing the object name as a string. Is that possible?

Sorry, I had some typos. Your fixed code looks good. Is it not working?

You can get variables by name using Key-Value coding, but it's *not* the right thing to do here - it's slow and it's overkill.

[icelandic]

Originally Posted by smasher

Sorry, I had some typos. Your fixed code looks good. Is it not working?

You can get variables by name using Key-Value coding, but it's *not* the right thing to do here - it's slow and it's overkill.

The fixed code is working great ( no errors or warnings ). I'm trying to make this method work in such a way where I don't need to hard code the objects in. Also, I'm originally a web programmer so I'm trying to associate how things are done with a framework vs. raw code.

[smasher]

If you still want to create the UIImageViews in Interface Builder but you don't want all of those vars / outlets, you can giver them all tags in IB and then locate them using [self.view viewWithTag:x] for adding to the array.

If you want to create them entirely in code, you can use initWithFrame: to create them , then add them as subviews in the current view and add them to the array.

[icelandic]

More or less, I want to have a string called "q0" and I want to get the id for the UIImageView object named q0. Google is not my friend for this problem.

I can change an image like this:

PHP Code:

q0.image = [UIImage imageNamed: imageLocation]; 


but I would like to change the image like this sudo code:

PHP Code:

NSString *objectName = @"q0";
id imageID = [objectName tag];
UIImageView *currentObject = [UIImageView initWithId: imageID];
currentObject.image = [UIImage imageNamed: imageLocation]; 


[icelandic]

bump

[jsd]

Smasher is right - you should do this with arrays. Just create an array of imageview objects, and if you need a filename that matches the position of the array index, you can use stringWithFormat to generate it.