NSURL、URL 和 NSData、数据 [英] NSURL, URL and NSData, Data

问题描述

我是 Swift 的新手.当我遇到 NSURL 和 URL 和 NSData 和 Data 时，我正在从互联网上提取图像.我真的很困惑.我使用哪些?我使用了以下代码，但我必须转换如下所示的类型.这样做的正确方法是什么，NSURL 和 URL 和 NSData 和 Data 之间有什么区别?有人请帮忙.

I'm new to Swift. I was pulling an image from the Internet when I came across NSURL and URL and NSData and Data. I'm really confused. Which ones do I use? I used the following code, but I had to convert the types as shown below. What is the proper way of doing this and what is the difference between NSURL and URL and NSData and Data? Somebody please help.

if let theProfileImageUrl = tweet.user.profileImageURL{
    if let imageData = NSData(contentsOf: theProfileImageUrl as URL){
        profileImageView.image = UIImage(data: imageData as Data)
    }
}

推荐答案

随着 Swift 3 的发布，许多类名去掉了 NS 前缀.它们应该只用于 Objective-C 代码.如果您正在编写 Swift 3 代码，则应仅使用更新的类.在这种情况下，URL 和 Data.

Many class names dropped the NS prefix with the release of Swift 3. They should only be used with Objective-C code. If you are writing Swift 3 code you should use only the updated classes. In this case, URL and Data.

然而，URL 被桥接到 NSURL 并且 Data 被桥接到 NSData 所以你可以在它们之间进行转换需要时.

However, URL is bridged to NSURL and Data is bridged to NSData so you can cast between them when needed.

if let theProfileImageUrl = tweet.user.profileImageURL {
    do {
        let imageData = try Data(contentsOf: theProfileImageUrl as URL)
        profileImageView.image = UIImage(data: imageData)
    } catch {
        print("Unable to load data: \(error)")
    }
}

我不知道 tweet.user.profileImageURL 在哪里定义，但它似乎在使用 NSURL 所以你需要将它转换为 URLcode> 在您的代码中.

I don't know where tweet.user.profileImageURL is defined but it appears to be using NSURL so you need to cast it to URL in your code.

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