iOS实现点击图片放大和长按保存图片的示例

Z时代
2024-01-10
分类：综合

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];    
  }  
}