数据写入到文件夹中

文件路径的含义

• var/mobile/Containers/Data/Application/0F51C27A-1282-4F11-8AB3-D8ACCC1A4A58/Documents/uzfs/A123456789/shareImage2/shareImage.png

• /var/mobile/Containers/Data/Application/应用名称/Documents/文件夹/shareImage.png（图片）

• base64转图片,把图片写入路径中

  NSData *decodedImageData = [[NSData alloc]
                           initWithBase64EncodedString:@"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" 
                           options:NSDataBase64DecodingIgnoreUnknownCharacters];
    
    UIImage *decodedImage = [UIImage imageWithData:decodedImageData];

    if (decodedImage == nil) {
        NSLog(@"base64转图片失败");
        return; 
    }else{
       //base64图片转成功，保存到某个路径下
           //1.看路径是否存在，不存在就创建
           BOOL isDir = NO;
           NSFileManager *fileManager = [NSFileManager defaultManager];
           //文件路径是否存在， 文件路径是否是路径 
           BOOL existed = [fileManager fileExistsAtPath:@"已知的文件夹路径字符串" isDirectory:&isDir];
    if (!(isDir == YES && existed == YES) )
    {
     BOOL    creatSuccess = [fileManager createDirectoryAtPath:createDir withIntermediateDirectories:YES attributes:nil error:nil];
        //标记为不备份，既不上传icloud
        
        if (creatSuccess) {
            
            NSError *error;
            BOOL success = [UIImageJPEGRepresentation(decodedImage, 0.5) 
writeToFile:imageFilePath options:NSDataWritingAtomic error:&error];
            
            if (success){
                   NSLog(@"图片写入文件夹成功");
            }else{
                 NSLog(@"图片写入文件夹失败");
                   }
        }else{
                 NSLog(@"文件夹创建失败");         
                 }
  }
}

• 程序开发遇到的报错信息

Error Domain=NSCocoaErrorDomain Code=512 "
未能将文件“shareImage.png”存储到文件夹“shareImage2”中。
" UserInfo={NSFilePath=/var/mobile/Containers/Data/Application/
0F51C27A-1282-4F11-8AB3-D8ACCC1A4A58/
Documents/uzfs/A123456789/shareImage2/shareImage.png, 
NSUnderlyingError=0x17424a2c0
{Error Domain=NSPOSIXErrorDomain Code=21 "Is a directory"}}

  fileExistsAtPath:param  参数必须是个路径

参考文章：http://blog.csdn.net/tpphy/article/details/48232353