【原创】iOS图片预览(支持缩放和移动)

1.传入图片

PreViewController.h：

#import <UIKit/UIKit.h>

@interface PreViewController : UIViewController

@property (nonatomic,strong) UIImage *preImage;

@end

2.图片加载

PreViewController.m：

#import "PreViewController.h"

@interface PreViewController () <UIScrollViewDelegate>

@property (weak, nonatomic) IBOutlet UIScrollView *preView;//滚动视图

@property (nonatomic,assign) CGFloat visibleWidth;//有效显示宽度
@property (nonatomic,assign) CGFloat visibleHeight;//有效显示高度
@property (nonatomic,assign) CGFloat originalWidth;//图片居中显示原始宽度
@property (nonatomic,assign) CGFloat originalHeight;//图片居中显示原始高度

@property (nonatomic,strong) UIImageView *photoView;//图片视图

@end

@implementation PreViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    [self loadPhoto];
}

- (void)loadPhoto
{
    self.originalWidth = ;
    self.originalHeight = ;
    self.visibleWidth = CGRectGetWidth([UIScreen mainScreen].bounds);
    self.visibleHeight = CGRectGetHeight([UIScreen mainScreen].bounds) - [[UIApplication sharedApplication] statusBarFrame].size.height - self.navigationController.navigationBar.frame.size.height;//除去状态栏和导航栏的有效显示高度
    CGFloat imageAspectRatio = self.preImage.size.width / self.preImage.size.height;//图片原始比例
    CGFloat viewAspectRatio = self.visibleWidth / self.visibleHeight;//有效显示区域比例
    if (imageAspectRatio > viewAspectRatio)
    {
        self.originalWidth = self.visibleWidth;
        self.originalHeight = self.originalWidth / imageAspectRatio;
    }
    else
    {
        self.originalHeight = self.visibleHeight;
        self.originalWidth = self.originalHeight * imageAspectRatio;
    }
    //居中
    CGFloat originalX = (self.visibleWidth - self.originalWidth) / 2.0;
    CGFloat originalY = (self.visibleHeight - self.originalHeight) / 2.0;

    self.photoView = [[UIImageView alloc] initWithImage:self.preImage];
    self.photoView.frame = CGRectMake(originalX, originalY, self.originalWidth, self.originalHeight);//图片视图在滚动视图即contentView内的位置大小

    //self.preView.contentSize = self.preImage.size;//设置为原始图片大小(可乘以倍数)
    //缩放设置
    //self.preView.zoomScale = 1.0;
    //self.preView.minimumZoomScale = 1.0;
    //self.preView.maximumZoomScale = self.preImage.size.width / self.originalWidth;
//优化

CGFloat contentWidth = MAX(self.preImage.size.width, self.visibleWidth);

CGFloat contentHeight = MAX(self.preImage.size.height, self.visibleHeight);

self.preView.contentSize = CGSizeMake(contentWidth, contentHeight);

self.preView.zoomScale = 1.0;

self.preView.minimumZoomScale = 1.0;

self.preView.maximumZoomScale = MAX(1.0, (self.preImage.size.width / self.originalWidth));

　　[self.preView addSubview:self.photoView];

} 

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView 
{
　　return self.photoView;//返回缩放视图 
} 

//根据缩放调整居中(当图片缩放到有效显示区域外则直接CGPointZero) 
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale 
{ 
　　CGRect rect = self.photoView.frame; 
　　CGFloat scaleWidth = MIN(self.visibleWidth, self.originalWidth * scale); 
　　CGFloat widthDistance = self.visibleWidth - scaleWidth; 
　　CGFloat scaleHeight = MIN(self.visibleHeight, self.originalHeight * scale); 
　　CGFloat heightDistance = self.visibleHeight - scaleHeight; 
　　rect.origin.x = widthDistance / 2.0; 
　　rect.origin.y = heightDistance / 2.0; 
　　[UIView animateWithDuration:0.25 animations:^{ self.photoView.frame = rect; }]; 
} 

@end

缩放过程中不会调整图片位置移动，只有在结束缩放后才动画调整居中显示，图片铺满有效显示区域后不存在居中问题，只要能显示全图即可。

此方法谈不上全面完善，只是目前看起来还不错，希望大家有好的方法可以分享~

转载请注明出处:http://www.cnblogs.com/HellerForever/p/6903534.html