xcode Swift 3：无法使用类型错误的参数列表调用 dataTask
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Swift 3: Cannot invoke dataTask with an argument list of type error
提问by Marat
I'm beginner in iOS. I have searched web and couldn't find answer that would solve my problem. Stuck and have no idea what to do and how to search for solution.
我是iOS初学者。我在网上搜索过，但找不到可以解决我的问题的答案。卡住了，不知道该怎么做以及如何寻找解决方案。
I'm following the tutorial which is based on Swift 2. The following method is showing error.
我正在关注基于 Swift 2 的教程。以下方法显示错误。
func downloadBooks(bookTitle: String) {
let stringURL = "GET https://www.googleapis.com/books/v1/volumes?q=\(bookTitle)"
guard let URL = URL(string: stringURL) else {
print("url problems")
return
}
let urlRequest = NSMutableURLRequest(url: URL)
let session = URLSession.shared
let task = session.dataTask(with: urlRequest) { (data: Data?, response: URLResponse?, error: Error?) in
}
task.resume()
}
I have made all adjustments suggested by Xcode, but no further hints.
我已经做了 Xcode 建议的所有调整，但没有进一步的提示。
Moreover, original portion of code from tutorial was like this:
此外，教程中的原始代码部分是这样的：
guard let URL = NSURL(string: stringURL) else {
print("url problems")
return
}
Then Xcode suggested to add as URLlike below:
然后Xcode建议添加as URL如下：
let urlRequest = NSMutableURLRequest(url: URL as URL)
Both of these versions are showing no error. So what is the difference? Which one should I use?
这两个版本都没有显示错误。那么区别是什么呢？我应该使用哪一种？
I would really appreciate any help!
我真的很感激任何帮助！
回答by vadian
In Swift 3 the compiler wants native URLRequest
在 Swift 3 中，编译器想要原生的 URLRequest
let urlRequest = URLRequest(url: url) // use a lowercase variable name, URL is a native struct in Swift 3
But with your particular syntax you don't even need the request
但是使用您的特定语法，您甚至不需要请求
let task = session.dataTask(with: url) { (data: Data?, response: URLResponse?, error: Error?) in ...
nor the annotations
也没有注释
let task = session.dataTask(with: url) { (data, response, error) in ...
