iOS 实现点击图片放大&长按保存图片

一：简介

在项目中免不了会遇到，实名认证上传身份证、绑定银行卡等功能。在实际操作中呢，会涉及到上传图片，在页面布局时，可能图片不是一张，考虑到布局的美观等因素，显示图片的位置变得很小，如果想查看上传的图片是否清晰，内容是否完整，可能就需要放大才能实现，下面就和大家分享一下我封装的一类，完美的实现了图片的缩放功能。

另外，这些博文都是来源于我日常开发中的技术总结，在时间允许的情况下，我会针对技术点分别分享iOS、Android两个版本，尽量附上demo以供大家参考，如果有其他技术点需要，可在文章后留言，我会尽全力帮助大家。

二：实现思路分析

给UIImageView添加手势
封装一个继承NSObject的FBYImageZoom类
写一个函数用来接收出入的UIImageView
根据传入的UIImageView重新绘制在Window中
添加放大后背景视图的颜色和透明度
使用动画放大展示ImageView
添加恢复ImageView原始尺寸的tap点击事件
完成之后将背景视图删掉

三：实现源码分析

根据实现思路分析，一步步进行编码实现：

1. 给UIImageView添加手势

self.myImageView = [[UIImageView alloc]initWithFrame:CGRectMake(50, 150, SCREEN_WIDTH-100, SCREEN_WIDTH-100)];
self.myImageView.image = [UIImage imageNamed:@"bankcard"];
//添加点击事件
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(scanBigImageClick:)];
[_myImageView addGestureRecognizer:tapGestureRecognizer];
[_myImageView setUserInteractionEnabled:YES];
[self.view addSubview:_myImageView];

2. 封装一个继承NSObject的FBYImageZoom类

#import <Foundation/Foundation.h>

#import <UIKit/UIKit.h>

@interface FBYImageZoom : NSObject

@end

3. 写一个函数用来接收出入的UIImageView

/**
 *  @param contentImageview 图片所在的imageView
 */
+(void)ImageZoomWithImageView:(UIImageView *)contentImageview;

4. 根据传入的UIImageView重新绘制在Window中

+(void)ImageZoomWithImageView:(UIImageView *)contentImageview{

    UIWindow *window = [UIApplication sharedApplication].keyWindow;
    [self scanBigImageWithImage:contentImageview.image frame:[contentImageview convertRect:contentImageview.bounds toView:window]];
}

5. 添加放大后背景视图的颜色和透明度

//当前视图
    UIWindow *window = [UIApplication sharedApplication].keyWindow;
    //背景
    UIView *backgroundView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)];
    [backgroundView setBackgroundColor:[UIColor colorWithRed:107/255.0 green:107/255.0 blue:99/255.0 alpha:0.6]];

6. 使用动画放大展示ImageView

    //动画放大所展示的ImageView
    [UIView animateWithDuration:0.4 animations:^{
        CGFloat y,width,height;
        y = ([UIScreen mainScreen].bounds.size.height - image.size.height * [UIScreen mainScreen].bounds.size.width / image.size.width) * 0.5;
        //宽度为屏幕宽度
        width = [UIScreen mainScreen].bounds.size.width;
        //高度 根据图片宽高比设置
        height = image.size.height * [UIScreen mainScreen].bounds.size.width / image.size.width;
        [imageView setFrame:CGRectMake(0, y, width, height)];
        //重要！ 将视图显示出来
        [backgroundView setAlpha:1];
    } completion:^(BOOL finished) {

    }];

7. 添加恢复ImageView原始尺寸的tap点击事件

//添加点击事件同样是类方法 -> 作用是再次点击回到初始大小
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(hideImageView:)];
[backgroundView addGestureRecognizer:tapGestureRecognizer];

/**
 *  恢复imageView原始尺寸
 */
+(void)hideImageView:(UITapGestureRecognizer *)tap{
    UIView *backgroundView = tap.view;
    //原始imageview
    UIImageView *imageView = [tap.view viewWithTag:1024];
    //恢复
    [UIView animateWithDuration:0.4 animations:^{
        [imageView setFrame:oldframe];
        [backgroundView setAlpha:0];
    } completion:^(BOOL finished) {
        [backgroundView removeFromSuperview];
    }];
}

8. 完成之后将背景视图删掉

//完成后操作->将背景视图删掉
[backgroundView removeFromSuperview];

四：项目实际使用

1. 引入封装类FBYImageZoom

#import "FBYImageZoom.h"

2. 给UIImageView添加手势

//添加点击事件
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(scanBigImageClick:)];

3. 调用封装类函数

//浏览大图点击事件
-(void)scanBigImageClick:(UITapGestureRecognizer *)tap{
    NSLog(@"点击图片");
    UIImageView *clickedImageView = (UIImageView *)tap.view;
    [FBYImageZoom ImageZoomWithImageView:clickedImageView];
}

好了，到这里点击图片放大到全屏就完成了

4. 长按保存图片

另外就是实现长按保存图片的功能，这个功能很简单

首先增加长按手势

    //创建长按手势
    UILongPressGestureRecognizer *longTap = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(imglongTapClick:)];
    //添加手势
    [_myImageView addGestureRecognizer:longTap];
然后长按手势弹出警告视图确认
-(void)imglongTapClick:(UILongPressGestureRecognizer*)gesture

{

    if(gesture.state==UIGestureRecognizerStateBegan)

    {

        UIAlertController *alertControl = [UIAlertController alertControllerWithTitle:@"保存图片" message:nil preferredStyle:UIAlertControllerStyleAlert];

        UIAlertAction *cancel = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {

            NSLog(@"取消保存图片");
        }];

        UIAlertAction *confirm = [UIAlertAction actionWithTitle:@"确认" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {

            NSLog(@"确认保存图片");

            // 保存图片到相册
            UIImageWriteToSavedPhotosAlbum(self.myImageView.image,self,@selector(imageSavedToPhotosAlbum:didFinishSavingWithError:contextInfo:),nil);

        }];

        [alertControl addAction:cancel];
        [alertControl addAction:confirm];

        [self presentViewController:alertControl animated:YES completion:nil];

    }

}

最后保存图片后的回调

- (void)imageSavedToPhotosAlbum:(UIImage*)image didFinishSavingWithError:  (NSError*)error contextInfo:(id)contextInfo

{

    NSString *message;

    if(!error) {

        message =@"成功保存到相册";

        UIAlertController *alertControl = [UIAlertController alertControllerWithTitle:@"提示" message:message preferredStyle:UIAlertControllerStyleAlert];

        UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {

        }];

        [alertControl addAction:action];

        [self presentViewController:alertControl animated:YES completion:nil];

    }else

    {

        message = [error description];


        UIAlertController *alertControl = [UIAlertController alertControllerWithTitle:@"提示" message:message preferredStyle:UIAlertControllerStyleAlert];

        UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {

        }];

        [alertControl addAction:action];

        [self presentViewController:alertControl animated:YES completion:nil];

    }

}

到这里实现点击图片放大和长按保存图片功能就都是实现了，demo源码已经放在github上。

五：项目展示
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