以编程方式显示另一个类的UIImageView属性

Question

Well, here's the situation: I've got...

• a custom class with an UIImageView -property, let's call it the Enemy -class
• a ViewController
• a NSMutableArray to help create multiple instances of Enemy (called enemies )

and what I want:

• be able to create an unlimited amount of Enemy -Instances through a method in my ViewController (like [self spawnEnemy]; , where self is the ViewController )
• and, subsequently, display the UIImageView property (let's call it " enemyImage ") on the view that is controlled by my ViewController

I've tried something like this:

-(Enemy *) spawnEnemy
 {
   Enemy *tempEnemy = [Enemy new];
   [enemies addObject:(Enemy*)tempEnemy];
   [self.view addSubview:(UIImageView*)[[enemies objectAtIndex:[enemies count]] enemyImage]];

   //randomLocation is declared in the Enemy-Class and just assigns a random 
   //CGPoint to self.enemyImage.center 
   [[enemies objectAtIndex:[enemies count]] randomLocation];

   return [[enemies objectAtIndex:[enemies count]]createEnemy];
 }

This runs without errors, randomLocation gets called (tried with NSLog), AND if I do something like this in another Method of ViewController :

[[self spawnEnemy] enemyTestMethod];

enemyTestMethod is being executed as well.

But still, no enemieView s are displayed on the screen... What am I doing wrong?

Thank you so much for your help and time.

==== Edit ====

Here's the relevant code from Enemy.h/Enemy.m:

@interface Enemy : NSObject
{
    UIImageView *enemyImage;   
}

@property (nonatomic, retain) IBOutlet UIImageView *enemyImage;

-(Enemy*) createEnemy;

//Enemy.m

@implementation Enemy

@synthesize enemyImage, speed;

-(Enemy *) createEnemy
{
    self.enemyImage = [[UIImageView alloc] init];
    [self.enemyImage setImage:[UIImage imageNamed:@"enemy.png"]];
    return self;
}

I also corrected the last line in the spawnEnemy -Method to properly send createEnemy.

Answer 1

You don't include the code in Enemy where you alloc/init the UIImageView property. Unless this code explicitly specifies a CGRect with the size and origin that you want, the view will be initialized with CGRectZero , which means even if you're correctly adding the subview (and it looks like you are) you still won't see it anywhere.

Post the Enemy code, and the problem will probably be immediately apparent.

Answer 2

Have you called -createEnemy before you added them to your view?

OK, you've got this checked.

Then maybe you should check as @MusiGenesis suggested.

To do this, you need to inspect the properties of your enemyImage.

You can do this in either of the following ways:

1. print its frame.size by:

   NSLog(@"enemyImage frame size: %@", NSStringFromCGRect(enemy.enemyImage));

2. set a breakpoint where you feel great, and check with your debugger:

   p (CGRect)[[enemy enemyImage] frame]