Set zoom for UIScrollView subclass - ios

Question

I am trying to subclass UIScrollView as "ImageScrollView". My class is pretty simple. It has an imageView as one of it's subviews that I want the class to zoom to.
ImageScrollView.h
#import <UIKit/UIKit.h>
#interface ImageScrollView : UIScrollView
#property (nonatomic, strong) UIImageView *imageView;
- (id)initWithFrame:(CGRect)frame andImage:(UIImage *)image;
#end
ImageScrollView.m
#import "ImageScrollView.h"
#interface ImageScrollView()
#property CGFloat scaleWidth;
#property CGFloat scaleHeight;
#end
#implementation ImageScrollView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (id)initWithFrame:(CGRect)frame andImage:(UIImage *)image
{
self = [super init];
if(self)
{
self.frame = frame;
self.imageView = [[UIImageView alloc]initWithImage:image];
[self addSubview:self.imageView];
self.contentSize = self.imageView.bounds.size;
self.scaleWidth = self.frame.size.width / image.size.width;
self.scaleHeight = self.frame.size.height / image.size.height;
CGFloat minScale = MIN(self.scaleWidth, self.scaleHeight);
self.maximumZoomScale = 1.0f;
self.minimumZoomScale = minScale;
[self setZoomScale:minScale];
[self zoomToRect:self.imageView.frame animated:NO];
}
return self;
}
#end
Adding the subclass as a subview of my viewcontroller works just fine except for the scrolling:
#import "ViewController.h"
#import "ImageScrollView.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
ImageScrollView *imageScrollView = [[ImageScrollView alloc]initWithFrame:self.view.bounds andImage:[UIImage imageNamed:#"1.jpg"]];
[self.view addSubview:imageScrollView];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
My first guess is that it has something to do with the delegate not implemented correctly for the subclass. Any suggestions?

Answer 1

Basics for zooming in a UIScrollView
Set scroll view delegate (making sure the class you set as delegate conforms to UIScrollViewDelegate. In your case this is something like self.delegate = self
Set minimumZoomScale or maximumZoomScale (or both)
Implement viewForZoomingInScrollView: to return view to zoom

Answer 2

Figured it out. I had to add the delegate declaration and remove the - (void)zoomToRect:(CGRect)rect animated:(BOOL)animated. Here's the answer in case anyone needs it:
ImageScrollView.h
#import <UIKit/UIKit.h>
#interface ImageScrollView : UIScrollView <UIScrollViewDelegate>
#property (nonatomic, strong) UIImageView *imageView;
- (id)initWithFrame:(CGRect)frame andImage:(UIImage *)image;
#end
ImageScrollView.m
#import "ImageScrollView.h"
#interface ImageScrollView()
#property CGFloat scaleWidth;
#property CGFloat scaleHeight;
#end
#implementation ImageScrollView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (id)initWithFrame:(CGRect)frame andImage:(UIImage *)image
{
self = [super init];
if(self)
{
self.frame = frame;
self.delegate = self;
self.imageView = [[UIImageView alloc]initWithImage:image];
[self addSubview:self.imageView];
self.contentSize = self.imageView.bounds.size;
self.scaleWidth = self.frame.size.width / image.size.width;
self.scaleHeight = self.frame.size.height / image.size.height;
CGFloat minScale = MIN(self.scaleWidth, self.scaleHeight);
self.maximumZoomScale = 1.0f;
self.minimumZoomScale = minScale;
[self setZoomScale:minScale];
}
return self;
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}