Symmetric zooming of image within scrollview in iOS - ios

Question

I am new to iPhone to iOS development. and I want a demo for zoom in and zoom out (symmetric zooming of image) a image within a scrollview in iOS.This is my code : in this code i have taken an image view within a scrollview(ZoomScrollView) and scrollview within a another Scrollview(scrollView_Gallery).Thanks in advance..
//ZoomGalleryViewController.m//
scrollView_Gallery.backgroundColor = [UIColor yellowColor];
scrollView_Gallery.delegate = self;
scrollView_Gallery.pagingEnabled = YES;
scrollView_Gallery.userInteractionEnabled = YES;
scrollView_Gallery.showsHorizontalScrollIndicator = NO;
scrollView_Gallery.showsVerticalScrollIndicator = NO;
[self.view addSubview:scrollView_Gallery];
if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPhone)
{
[scrollView_Gallery setContentSize:CGSizeMake(self.view.frame.size.width*[arrayUrl count],self.view.frame.size.height)];
}
else if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPad)
{
[scrollView_Gallery setContentSize:CGSizeMake([[UIScreen mainScreen] bounds].size.width*[arrayUrl count],[[UIScreen mainScreen] bounds].size.height)];
}
for (int i = 0; i < [arrayUrl count]; i++)
{
zoomScrollView = [[ZoomScrollView alloc]init];
zoomScrollView.backgroundColor = [UIColor redColor];
[zoomScrollView setContentSize:CGSizeMake(zoomScrollView.contentSize.width,zoomScrollView.frame.size.height)];
CGRect frame = scrollView_Gallery.frame;
frame.origin.x = (frame.size.width)* i;
frame.origin.y = 0;
zoomScrollView.frame = frame;
zoomScrollView.imageView.contentMode = UIViewContentModeScaleAspectFit;
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[[arrayUrl objectAtIndex:i]objectForKey:#"photopath"]]];
__weak UIImageView *weakImageView = zoomScrollView.imageView;
zoomScrollView.imageView.tag = i;
zoomScrollView.ZOOM_VIEW_TAG = zoomScrollView.imageView.tag;
[zoomScrollView.imageView setImageWithURLRequest:request
placeholderImage:nil
success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image)
{
NSLog(#"image=%f,imageheight=%f",image.size.width,image.size.height);
UIImageView *strongImageView = weakImageView; // make local strong reference to protect against race conditions
strongImageView.frame = CGRectMake(0,0,image.size.width*image.scale, image.size.height*image.scale);
strongImageView.center = scrollView_Gallery.center;
NSLog(#"image11 = %f, imageheight11 = %f",image.size.width*image.scale, image.size.height*image.scale);
NSLog(#"imageScale = %f",image.scale);
if (!strongImageView) return;
[UIView transitionWithView:strongImageView
duration:0.3
options:UIViewAnimationOptionTransitionCrossDissolve animations:^{
strongImageView.image = image;
}
completion:NULL];
//[scrollView_Gallery setContentOffset:CGPointMake(strongImageView.frame.size.width * (indexNumber+1), 0)];
}failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error){
NSLog(#"Request failed with error: %#", error);
}];
[scrollView_Gallery addSubview:zoomScrollView];
[zoomScrollView setContentSize:CGSizeMake(zoomScrollView.contentSize.width,zoomScrollView.frame.size.height)];
if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPhone)
{
[scrollView_Gallery setContentOffset:CGPointMake(self.view.frame.size.width * (indexNumber), 0)];
}
else if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPad)
{
[scrollView_Gallery setContentOffset:CGPointMake([[UIScreen mainScreen] bounds].size.width * (indexNumber), 0)];
}
// ZoomScrollView.h//
#import <UIKit/UIKit.h>
#interface MRZoomScrollView : UIScrollView <UIScrollViewDelegate>
{
UIImageView *imageView;
}
#property (nonatomic, retain) UIImageView *imageView;
#end
// MRZoomScrollView.m//
#import "MRZoomScrollView.h"
#define MRScreenWidth CGRectGetWidth([UIScreen mainScreen].applicationFrame)
#define MRScreenHeight CGRectGetHeight([UIScreen mainScreen].applicationFrame)
#interface MRZoomScrollView (Utility)
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center;
#end
#implementation MRZoomScrollView
#synthesize imageView;
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.delegate = self;
self.frame = CGRectMake(0, 0, MRScreenWidth, MRScreenHeight);
[self initImageView];
}
return self;
}
- (void)initImageView
{
imageView = [[UIImageView alloc]init];
// The imageView can be zoomed largest size
imageView.frame = CGRectMake(0, 0, MRScreenWidth * 2.5, MRScreenHeight * 2.5);
imageView.userInteractionEnabled = YES;
[self addSubview:imageView];
[imageView release];
// Add gesture,double tap zoom imageView.
UITapGestureRecognizer *doubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleDoubleTap:)];
[doubleTapGesture setNumberOfTapsRequired:2];
[imageView addGestureRecognizer:doubleTapGesture];
[doubleTapGesture release];
float minimumScale = self.frame.size.width / imageView.frame.size.width;
[self setMinimumZoomScale:minimumScale];
[self setZoomScale:minimumScale];
}
#pragma mark - Zoom methods
- (void)handleDoubleTap:(UIGestureRecognizer *)gesture
{
float newScale = self.zoomScale * 1.5;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gesture locationInView:gesture.view]];
[self zoomToRect:zoomRect animated:YES];
}
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center
{
CGRect zoomRect;
zoomRect.size.height = self.frame.size.height / scale;
zoomRect.size.width = self.frame.size.width / scale;
zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0);
zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0);
return zoomRect;
}
#pragma mark - UIScrollViewDelegate
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return imageView;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
[scrollView setZoomScale:scale animated:NO];
}

Answer 1

You can do it by using UIScrollView and enable enabledZoom ON.
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
in viewDidLoad method paste this code
- (void)viewDidLoad {
[super viewDidLoad];
self.scrollView.minimumZoomScale=0.5;
self.scrollView.maximumZoomScale=6.0;
self.scrollView.contentSize=CGSizeMake(1280, 960);
self.scrollView.delegate=self;
}

Answer 2

Look at this tutorial, it was helpful for me:

Answer 3

Assuming you have a property scrollView, try the following code in your view controller s viewDidLoad or viewWillAppear methods:
self.scrollView.minimumZoomScale=1.0;
self.scrollView.maximumZoomScale=2.0;
self.scrollView.contentSize=self.scrollView.frame.size;
self.scrollView.bounces=YES;
self.scrollView.delegate=self;
Let your view controller conform to the UIScrollViewDelegate protocol. And implement the delegate method :
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;// return the imageView inside the scrollview which has to be scaled.
}