Changing Image Using Button iPhone

Question

Hi,

I have a UIImageView *picture

and a UIButton *next

and an - (IBAction)next { }

I want to change the image on the view but only if the image equals... for example img1

But using the same button I want to also be able to change the picture if the image = img2 but to a different image (img3)

So far I have this code but it gives me errors please could you help:

Code:

- (IBAction)next {
    if (picture UIImage = imageNamed:@"img01.jpg") {
    [picture setImage: [UIImage imageNamed:@"img02.jpg"
    }
    if (picture UIImage = imageNamed:@"img02.jpg") {
    [picture setImage: [UIImage imageNamed:@"img03.jpg"
 }
}

Please help

Thanks,

Will

Answer 1

- (IBAction)next {
    if ([[picture image] isEqual: [UIImage imageNamed:@"img01.jpg"]]) {

       [picture setImage: [UIImage imageNamed:@"img02.jpg"]];

    } else if ([[picture image] isEqual: [UIImage imageNamed:@"img02.jpg"]]) {

       [picture setImage: [UIImage imageNamed:@"img03.jpg"]];
    }
}

Also, this is a pretty rudimentary way of changing the image. A more elegant way would be to have a global int that had the current image index, so clicking "next" would simply increase that count. Then, if an image exists with that name, switch to it:

// Declare index in Header.h

index=0;

- (IBAction)next {
    index++;
    // Set imageCount to as many images as are available
    int imageCount=2;
    if (index<=imageCount) {
        NSString* imageName=[NSString stringWithFormat:@"img%02i", index];
        [picture setImage: [UIImage imageNamed: imageName]];
    }
}

Answer 2

Subclass UIImageView and add a enum property in the header:

typedef enum _PictureType {
    PictureTypeFirstImage = 0,
    PictureTypeSecondImage,
    PictureTypeThirdImage,
    PictureTypes
} PictureType;

@interface MyImageView : UIImageView {
    PictureType type;
}

@property (readwrite) PictureType type;

In the implementation:

@synthesize type;

When initializing your picture:

[picture setImage:[UIImage imageNamed:@"img01.jpg"]];
picture.type = PictureTypeFirstImage;

In your action method:

- (IBAction) next {
    switch (picture.type) {
        case (PictureTypeFirstImage): {
            [picture setImage:[UIImage imageNamed:@"img02.jpg"]];
            picture.type = PictureTypeSecondImage;
            break;
        }
        case (PictureTypeSecondImage): {
            [picture setImage:[UIImage imageNamed:@"img03.jpg"]];
            picture.type = PictureTypeThirdImage;
            break;
        }
        default:
            break;
    }
}

Answer 3

- (IBAction)next {
    picture.tag++;
    [picture setImage:[UIImage imageNamed:
             [NSString stringWithFormat:@"img%02d.jpg",1+(picture.tag%2)]
    ]];
}

should be the simplest solution.

edit on first click, goes to img02.jpg, on second click back to img01.jpg again. Increase the 2 to allow for img03.jpg etc.

Answer 4

I figured it out now all I did was forget to put .jpg on the end of the img%i ;)

- (IBAction)next {
     static int index = 0;  // <-- here
    index++;
    // Set imageCount to as many images as are available
    int imageCount=16;
    if (index<=imageCount) {
        NSString* imageName=[NSString stringWithFormat:@"img%i", index];
        [picture setImage: [UIImage imageNamed: imageName]];
    }
}