Adding Pictures to UIScrollView - slide switch effect using array

Question

I have seen many of the posts on this site as well as many more on Google, and I am stuck on what I am sure is something easy. I am new to iOS, and I have most likely been reading the other posts incorrectly. I am trying to learn and write my own code with my own logic and attempts, so mine looks a good deal different than the others I have found... which is why it doesn't work I am sure!

I am trying to get a picture show using swipe from right to left, but I want the next picture to be pulled over and slide into place, instead of the instant switch I have done here. Based on many recommendations, I am trying to use a UIScrollView. I can't get anything to load and the app crashes on the last line of loadImages. I have debugged but can't seem to figure out why it is not showing the subView.

Here is my viewDidLoad:

    [super viewDidLoad];
// Do any additional setup after loading the view.
i = 0;
//add UIPanGestureRecognizer
UIPanGestureRecognizer *aPan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(loadImages)];
[aPan setMaximumNumberOfTouches:1];
[aPan setMinimumNumberOfTouches:1];
[self.view addGestureRecognizer:aPan];


_PhotoBundle = [[NSBundle mainBundle] pathsForResourcesOfType:@".jpg"inDirectory:@"Otter_Images"];

_PhotoArray = [[NSMutableArray alloc] initWithCapacity:_PhotoBundle.count];
for (NSString* path in _PhotoBundle)
{
    [_PhotoArray addObject:[UIImage imageWithContentsOfFile:path]];
}

[self loadImages];

Here is my loadImages:

-(void)loadImages

{ NSLog(@"in loadImages");

_currentImage = [_PhotoArray objectAtIndex:i];
_nextImage = [_PhotoArray objectAtIndex:i + 1];
_prevImage = [_PhotoArray objectAtIndex:i -1];
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
[scrollView setScrollEnabled:YES];
[scrollView setClipsToBounds:YES];

if (i <= _PhotoArray.count)
{
    [scrollView addSubview:_currentImage]; ////crash!!!!
}
else
{
    _currentImage = [_PhotoArray objectAtIndex:0];
    [scrollView addSubview:_currentImage]; /// Crash!!!!
}

NSLog(@"end of loadImages");

}

I have left off functionality until I can get one image loaded. I will then add the functionality for the slide.... I hope I am approaching this right.

Thank you very much for any help!!

edit:

Here is my interface in my .m that sets up the ImageViews:

@interface ScrollViewViewController ()

@property (nonatomic, retain) NSArray *PhotoBundle;
@property (nonatomic, retain) NSMutableArray *PhotoArray;
@property (nonatomic, retain) UIImageView *currentImage;
@property (nonatomic, retain) UIImageView *nextImage;
@property (nonatomic, retain) UIImageView *prevImage;

@end

If your question involves a crash, please include the crash log, it is a great help. — jrturton
– jrturton, Commented Oct 26, 2012 at 21:24
[scrollView addSubview:_currentImage]; ////crash!!!! - This will crash because you are supposed to add an imageview in scrollview and set its imageview.image = _currentImage. You cant directly add it like this. — iDev
– iDev, Commented Oct 26, 2012 at 23:41
Thanks, I can't quite figure out what you mean? Set the scroll view to the image? or set the subview to the image? — Siriss
– Siriss, Commented Oct 27, 2012 at 4:17

jrturton · Accepted Answer · 2012-10-26 21:29:08Z

1

You are adding UIImage objects as subviews. You can't do this. You have to make a UIImageView first - only UIView subclasses can be added as subviews.

Making an image view is simple - you can alloc/initWithImage: and pass in your image object. You'll need to adjust the frames of each image view otherwise they'll all be on top of each other.

Additionally, you don't need a pan gesture recogniser if you're using a scroll view. The scroll view handles this for you.

answered Oct 26, 2012 at 21:29

jrturton

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6 Comments

Siriss Over a year ago

Thank for the response. my _currentView object is an UIImageView setup in the @interface. Can you not add a UIImage to a UIImageView? do I need to create a new UIIMageView each time?

jrturton Over a year ago

There is no _currentView that I can see in your code. You can assign a new image to an existing image view, yes, just set the .image property.

Siriss Over a year ago

I had to leave town, sorry for the delay. I just edited my question to include my interface where I setup my _currentImage.... I realize I said _currentView in my last post and I am sorry for the confusion. I am trying your suggestions now.

Siriss Over a year ago

so when I add the .image to the _currentImage UIImageView, and add that as a subview to the scrollView it does not crash on that line. I get a white screen which I imagine has to do with frames.

jrturton Over a year ago

Probably, yes. Check the value of self.currentImage in the debugger, it may be nil (I can't see where you set it up) or have an odd frame.

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