ios 图片输出到文件

NSData *imageData = ...
NSArray *paths =NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:
                             [NSString stringWithFormat:@"demo.png"]];  // 保存文件的名称
    BOOL result = [imageData writeToFile:filePath atomically:NO];
       
      // BOOL result =[UIImagePNGRepresentation(image)writeToFile:filePath   atomically:YES]; // 保存成功会返回YES```