swift - Firebase 存储检索图像

Question

我正在尝试了解 Firebase 存储。我在网上看到并尝试了两种获取图像的方法。这两者有什么区别？ (两者都有效)。

因此，当我从 Firebase 数据库获取 photoUrl 后:

1.

if let data = NSData(contentsOfURL: NSURL(string:photoUrl)!)
{
     let myImage = UIImage(data: data)!

     MyImageCache.sharedCache.setObject(myImage, forKey: self.key)
     //etc
 }

2.

 self.storage.referenceForURL(photoUrl).dataWithMaxSize(1 * 1024 * 1024) { (data, error) -> Void in
    if (error != nil)
    {
         print(error)
    }
    else
    {
        let myImage = UIImage(data: data!)

        MyImageCache.sharedCache.setObject(myImage!, forKey: self.key) 
        //etc       
    }
}

Answer 1

关于第一种方法，您不应该将其用于网络调用。来自文档:

Do not use this synchronous method to request network-based URLs. For network-based URLs, this method can block the current thread for tens of seconds on a slow network, resulting in a poor user experience, and in iOS, may cause your app to be terminated. Instead, for non-file URLs, consider using the dataTaskWithURL:completionHandler: method of the NSURLSession class. See URL Session Programming Guide for details.

第二种方法内置于 Firebase 框架中，为您提供下载图像的便捷方法，即它为您提供指定图像大小的选项。这可能针对获取图像进行了优化，并且在大多数情况下是首选方法。