Iphone – Does UIImage’s -imageNamed: method work for image files stored in ‘Documents’

documentsiphoneuiimageuikit

My app downloads a small image file from a remote server and I am trying to display it along with some other small image files that are pre-installed in the app. I am using [UIImage imageNamed:@"TheImageName.png"] to get the images (see below for more detail). The pre-installed images display as expected but the image in my apps 'Documents' directory is no where to be found. Should I be using -imageNamed for an image in 'Documents' or some other method?

UIImage* documentsImage = [UIImage imageNamed:@"TheImageName.png"];
UIImageView* anImageView = [[UIimageView alloc] initWithImage:documentsImage];
[self.view addSubview:anImageView];

Best Answer

Ah, nevermind. I found that using [UIImage imageWithContentsOfFile:filePath] works for this. imageNamed just returns nil.

Related Solutions

R – Memory management when using UIImage

[UIImage imageNamed:]

caches the image you're loading into memory. This is great if you want to reuse the same set of images over and over again, but if you are constantly showing different (or large) images, then you should use:

NSString *fileLocation = [[NSBundle mainBundle] pathForResource:fileName ofType:extension];
NSData *imageData = [NSData dataWithContentsOfFile:fileLocation];

[UIImage imageWithData:imageData];

instead.

Cocoa-touch – How to zoom in/out an UIImage object when user pinches screen

As others described, the easiest solution is to put your UIImageView into a UIScrollView. I did this in the Interface Builder .xib file.

In viewDidLoad, set the following variables. Set your controller to be a UIScrollViewDelegate.

- (void)viewDidLoad {
    [super viewDidLoad];
    self.scrollView.minimumZoomScale = 0.5;
    self.scrollView.maximumZoomScale = 6.0;
    self.scrollView.contentSize = self.imageView.frame.size;
    self.scrollView.delegate = self;
}

You are required to implement the following method to return the imageView you want to zoom.

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return self.imageView;
}

In versions prior to iOS9, you may also need to add this empty delegate method:

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
}

The Apple Documentation does a good job of describing how to do this:

Best Answer

Related Solutions

R – Memory management when using UIImage

Cocoa-touch – How to zoom in/out an UIImage object when user pinches screen

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