UIScroll center image - ios

Question

I've edited this question a few times, but can still not get my images to center inside a uiview. I want them to be able to rotate like the photos app and display the correct size when a user brings them up. Here is what I'm working with:
In my PhotoViewController.h
#import <UIKit/UIKit.h>
#protocol PhotoViewControllerDelegate <NSObject>
- (void)toggleChromeDisplay;
#end
#interface PhotoViewController : UIViewController <UIScrollViewDelegate, UIGestureRecognizerDelegate>
#property (nonatomic, strong) UIImage *photo;
#property (nonatomic) NSUInteger num;
//Delegate
#property (nonatomic, strong) id<PhotoViewControllerDelegate> photoViewControllerDelegate;
#property (nonatomic, strong) UIImageView *photoImgView;
#property (nonatomic, strong) UIScrollView *scrollView;
#end
In my PhotoViewController.m:
#import "PhotoViewController.h"
#interface PhotoViewController ()
#end
#implementation PhotoViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
//todo
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
CGRect screenBounds = self.view.bounds;
//scroll view
_scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, screenBounds.size.width, screenBounds.size.height)];
_scrollView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
_scrollView.pagingEnabled = NO;
_scrollView.scrollEnabled = YES;
[_scrollView setBackgroundColor:[UIColor blueColor]];
//Zoom Properties
_scrollView.maximumZoomScale = 6.0;
_scrollView.minimumZoomScale = 1.0;
_scrollView.bouncesZoom = YES;
_scrollView.delegate = self;
_scrollView.zoomScale = 1.0;
_scrollView.contentSize = _photoImgView.bounds.size;
[_scrollView setShowsHorizontalScrollIndicator:NO];
[_scrollView setShowsVerticalScrollIndicator:NO];
[self photoBounds];
[self.view addSubview: _scrollView];
//Add the UIImageView
_photoImgView = [[UIImageView alloc] initWithImage:_photo];
_photoImgView.image = _photo;
_photoImgView.clipsToBounds = YES;
_photoImgView.contentMode = UIViewContentModeScaleAspectFit;
_photoImgView.autoresizingMask = (UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin);
[_photoImgView setUserInteractionEnabled:YES];
[_scrollView addSubview: _photoImgView];
//Set up Gesture Recognizer
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGestureCaptured:)];
UITapGestureRecognizer *dTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(dTapGestureCaptured:)];
dTap.numberOfTapsRequired = 2;
[singleTap requireGestureRecognizerToFail:dTap];
//Gesture Methods
[self.scrollView addGestureRecognizer:singleTap];
[self.scrollView addGestureRecognizer : dTap];
}
- (void)photoBounds
{
UIInterfaceOrientation statusbar = [[UIApplication sharedApplication] statusBarOrientation];
CGSize photoBounds = _photo.size;
CGSize scrollBounds = self.view.bounds.size;
CGRect frameToCenter = [_photoImgView frame];
float newHeight = (scrollBounds.width / photoBounds.width) * photoBounds.height;
float newWidth = (scrollBounds.height / photoBounds.height) * photoBounds.width;
float yDist = fabsf(scrollBounds.height - newHeight) / 2;
float xDist = fabsf(scrollBounds.width - newWidth) / 2;
//Width Larger
if (photoBounds.width >=photoBounds.height) {
NSLog(#"portrait width");
_photoImgView.frame = CGRectMake(0, 0, scrollBounds.width, newHeight);
frameToCenter.origin.y = yDist;
}
//Height Larger
else if (photoBounds.height > photoBounds.width) {
NSLog(#"portrait height");
_photoImgView.frame = CGRectMake(0, 0, newWidth, scrollBounds.height);
frameToCenter.origin.x = xDist;
}
//Square
else {
NSLog(#"portrait square");
if ((statusbar == 1) || (statusbar == 2)) {
_photoImgView.frame = CGRectMake(0, 0, scrollBounds.width, newHeight);
frameToCenter.origin.y = yDist;
} else {
_photoImgView.frame = CGRectMake(0, 0, newWidth, scrollBounds.height);
frameToCenter.origin.x = xDist;
}
}
}
//Rotation Magic
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
//later
}
- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
[self photoBounds];
}
- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
//
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return YES;
}
//Zoom Ability
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.photoImgView;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
NSLog(#"scale %f", scale);
NSLog(#"done zooming");
}
//Touches Control
- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)gesture
{
//CGPoint touchPoint=[gesture locationInView:_scrollView];
NSLog(#"touched");
NSLog(#"single touch");
[self performSelector:#selector(callingHome) withObject:nil afterDelay:0];
}
- (void)dTapGestureCaptured:(UITapGestureRecognizer *)gesture
{
NSLog(#"double touched");
}
- (void)panGestureCaptured:(UIPanGestureRecognizer *)gesture
{
NSLog(#"pan gesture");
}
- (void)callingHome {}
#end
The overall issue is that I can not get my picture to display correctly and be able to zoom on just it, no space around it and It needs to be the correct dimensions on load. I've been struggling with it for a few days.
Any help?

Answer 1

I have resolved a similar problem using a really simple subclass of UIScrollView of my own. You can take a look at it here - https://gist.github.com/ShadeApps/5a29e1cea3e1dc3df8c8. Works like charm for me.
That's how you init it:
scrollViewMain.delegate = self;
scrollViewMain.minimumZoomScale = 1.0;
scrollViewMain.maximumZoomScale = 3.0;
scrollViewMain.contentSize = imageViewMain.frame.size;
scrollViewMain.backgroundColor = [UIColor blackColor];
scrollViewMain.tileContainerView = imageViewMain;

Answer 2

There is awesome blog post about this problem from Peter Steinberger: http://petersteinberger.com/blog/2013/how-to-center-uiscrollview/