iOS截屏和读取

除了直接使用手机按键截屏，在App中我们也可以通过代码去实现截屏功能。以下是我的工程里封装的截屏方法，在此记录一下。
1.使用drawViewHierarchyInRect方法截取当前屏幕

[view drawViewHierarchyInRect:view.frame afterScreenUpdates:YES];

2.把截取的当前UIView转成UIImage

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

3.图片转成NSData二进制，保存到沙盒中

 NSData * imageData = UIImagePNGRepresentation(image);
[imageData writeToFile:fullPathToFile atomically:NO];

4.读取文件下的图片

完整示例代码

1.自定义一个继承于NSObject的模型类PubSysFunc

//截屏方法
+ (void)screenShotAction:(UIView *)view{
    //使用respondsToSelector方法判断，防止异常时崩溃
    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]){
        UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, [UIScreen mainScreen].scale);
    } else {
        UIGraphicsBeginImageContext(view.bounds.size);
    }
    //截取当前屏幕
    [view drawViewHierarchyInRect:view.frame afterScreenUpdates:YES];
    //视图转成UIImage
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    //保存图片到沙盒
    NSData * imageData = UIImagePNGRepresentation(image);
    //自定义文件存储路径
    NSString *folderPath = [PubSysFunc createUserDataFolder:@"Images"];
    UInt64 time = [[NSDate date] timeIntervalSince1970]*1000;
    NSString *imageName = [NSString stringWithFormat:@"%llu.png",time];
    NSString * fullPathToFile = [folderPath stringByAppendingPathComponent:imageName];
   //写入文件
    [imageData writeToFile:fullPathToFile atomically:NO];
}
//在UserData目录下创建文件夹
//#define  USERDATAPATH @"xxx/xxx/UserData"
+ (NSString *)createUserDataFolder:(NSString *)folderName{
    //Document目录
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [paths objectAtIndex:0];
    NSString *userPath = [path stringByAppendingPathComponent:USERDATAPATH];
    NSString *folderPath = [userPath stringByAppendingPathComponent:folderName];
    NSFileManager *fm = [NSFileManager defaultManager];
    if(![fm fileExistsAtPath:folderPath]) {
        //创建文件夹
        if (![[NSFileManager defaultManager] createDirectoryAtPath:folderPath withIntermediateDirectories:YES attributes:nil error:nil]) {
            return nil;
        }
    }
    return folderPath;
}
//得到该路径下的所有指定后缀名的文件
//这里传入extensionName值用于区分是图片还是视频
+ (NSArray *)getAllFilePathWithFolderPath:(NSString *)path extension:(NSString *)extensionName{
    if (path == nil) {
        //目标文件不存在
        return nil;
    };
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSDirectoryEnumerator *myDirectoryEnumerator = [fileManager enumeratorAtPath:path];
    //用来存目录名字的数组
    NSMutableArray *filePathArray = [[NSMutableArray alloc]init];   
    NSString *file = nil;
    //遍历当前目录
    while((file=[myDirectoryEnumerator nextObject])){
        if([[file pathExtension] isEqualToString:extensionName]){
            //存到数组
            [filePathArray addObject:[path stringByAppendingPathComponent:file]];
        }
    }
    return filePathArray;
}

2.在VC中调用截屏方法

//#define KEYWIN [[UIApplication sharedApplication] keyWindow]
- (void)screenshot{
    [PubSysFunc screenShotAction:KEYWIN];
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"提示" message:@"保存成功" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *cancelAction1 = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
    }];
    [alert addAction:cancelAction1];
    AppDelegate *delegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
    [delegate.window.rootViewController presentViewController:alert animated:YES completion:nil];
}

3.在VC中读取文件

- (void)getDataSource
{
    NSString *path = [PubSysFunc getDestDocPath:[NSString stringWithFormat:@"%@/Images",USERDATAPATH]];
    NSArray *nameList = [PubSysFunc getAllFilePathWithFolderPath:path extension:@"png"];
   //nameList即为USERDATAPATH路径下获取到的图片
}