条件绑定的初始化器必须具有可选类型，而不是'String'

Here is a fun issue I'm running into after updating to Swift 2.0

更新到Swift 2.0后，我遇到了一个有趣的问题

The error is on the if let url = URL.absoluteString line

错误在if let url = url上。absoluteString线

func myFormatCompanyMessageText(attributedString: NSMutableAttributedString) -> NSMutableAttributedString
{
    // Define text font
    attributedString.addAttribute(NSFontAttributeName, value: UIFont(name: "Montserrat-Light", size: 17)!, range: NSMakeRange(0, attributedString.length))

    return attributedString
}

func textView(textView: UITextView, shouldInteractWithURL URL: NSURL, inRange characterRange: NSRange) -> Bool {
    if let url = URL.absoluteString {
        if #available(iOS 8.0, *) {
            VPMainViewController.showCompanyMessageWebView(url)
        }
    }
    return false
}

3 个解决方案

#1

The compiler is telling you that you can't use an if let because it's totally unnecessary. You don't have any optionals to unwrap: URL is not optional, and the absoluteString property isn't optional either. if let is used exclusively to unwrap optionals. If you want to create a new constant named url, just do it:

编译器告诉你，你不能使用if let，因为它完全没有必要。您没有展开的选项:URL不是可选的，absoluteString属性也不是可选的。如果let被专门用于展开选项。如果您想要创建一个新的名为url的常量，只需这样做:

func textView(textView: UITextView, shouldInteractWithURL URL: NSURL, inRange characterRange: NSRange) -> Bool {
    let url = URL.absoluteString
    if #available(iOS 8.0, *) {
        VPMainViewController.showCompanyMessageWebView(url)
    }
    return false
}

However, sidenote: having a parameter named URL and a local constant named url is mighty confusing. You might be better off like this:

但是，sidenote:有一个名为URL的参数和一个名为URL的本地常量非常令人困惑。你最好这样:

func textView(textView: UITextView, shouldInteractWithURL URL: NSURL, inRange characterRange: NSRange) -> Bool {
    if #available(iOS 8.0, *) {
        VPMainViewController.showCompanyMessageWebView(URL.absoluteString)
    }
    return false
}

#2

Here is your working function:

这是你的工作职能:

func textView(textView: UITextView, shouldInteractWithURL URL: NSURL?, inRange characterRange: NSRange) -> Bool {
    if let url = URL?.absoluteString {
        if #available(iOS 8.0, *) {
            VPMainViewController.showCompanyMessageWebView(url)
        }
    }
    return false
}

In your function argument make your URL optional.

在函数参数中，使URL可选。

And unwrap it this way:

然后这样展开:

if let url = URL?.absoluteString {

    //your code.
}

#3

absoluteString isn't an optional value, its just a String. You can check if the URL variable is nil

absoluteString不是一个可选的值，它只是一个字符串。您可以检查URL变量是否为nil

if let url = yourURLVariable {
    // do your textView function
} else {
    // handle nil url
}

#1

func textView(textView: UITextView, shouldInteractWithURL URL: NSURL, inRange characterRange: NSRange) -> Bool {
    let url = URL.absoluteString
    if #available(iOS 8.0, *) {
        VPMainViewController.showCompanyMessageWebView(url)
    }
    return false
}