ios 根据手势放大或缩小图片

ios 根据手势放大或缩小图片

当用户需要根据自定义大小图片时，需要提供UIPinchGestureRecognizer来识别用户的手势。具体的步骤：

1、新建xcode工程，选择View-based Application，工程名PhotoPanDemo

2、添加一张图片到Resources目录下，这里的图片命名为feiche.jpg

3、打开PhotoPanDemoViewController.h文件，创建UIImageView和UIView对象并添加手势的委托类，

代码：#import <UIKit/UIKit.h>

@interface PhotoPanDemoViewController : UIViewController <UIGestureRecognizerDelegate>{

UIImageView *imageView;CGFloat lastScale;UIView *holderView;

}

-(void)scale:(id)sender;

@end

4、打开PhotoPanDemoViewController.m文件，代码：

//// PhotoPanDemoViewController.m

// PhotoPanDemo//

// Created by jordy on 11-4-6.

// Copyright 2011 vsp. All rights reserved.//

#import "PhotoPanDemoViewController.h"

@implementation PhotoPanDemoViewController

- (void)viewDidLoad {

[super viewDidLoad];

UIView *rootView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 768, 1024)];

rootView.backgroundColor = [UIColor yellowColor];

self.view = rootView;

UIImage *image = [UIImage imageNamed:@"feiche.jpg"];

holderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, image.size.width, image.size.height)];

imageView = [[UIImageView alloc] initWithFrame:[holderView frame]];[imageView setImage:image];

[holderView addSubview:imageView];

//拧的手势

UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scale:)];

[pinchRecognizer setDelegate:self];

[holderView addGestureRecognizer:pinchRecognizer];

[rootView addSubview:holderView];

[rootView release];

}

-(void)scale:(id)sender {

[self.view bringSubviewToFront:[(UIPinchGestureRecognizer*)sender view]];

//当手指离开屏幕时,将lastscale设置为1.0

if([(UIPinchGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded) 

{lastScale = 1.0;

return;}

CGFloat scale = 1.0 - (lastScale - [(UIPinchGestureRecognizer*)sender scale]);

CGAffineTransform currentTransform = [(UIPinchGestureRecognizer*)sender view].transform;

CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);

[[(UIPinchGestureRecognizer*)sender view] setTransform:newTransform];

lastScale = [(UIPinchGestureRecognizer*)sender scale];

}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer 

{

return ![gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]];

}/

/ Override to allow orientations other than the default portrait orientation.

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

 {return YES;}

- (void)didReceiveMemoryWarning

 {// Releases the view if it doesn't have a superview.

[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.

}

- (void)viewDidUnload {

// Release any retained subviews of the main view.

// e.g. self.myOutlet = nil;

}

- (void)dealloc {

[super dealloc];

[imageView release];

[holderView release];

}

@end