根据identifier从StoryBoard中获取对象，UIButton的图片文件位置

- (id)readViewControllerFromStoryBoardWithIdentifier:(NSString *)identifier

{

    return [[UIStoryboard storyboardWithName:@"ELVStoryBoard" bundle:nil] instantiateViewControllerWithIdentifier:identifier];

}

 

[backBtn setImageEdgeInsets:UIEdgeInsetsMake(0, 0, 0, 44)];