如何根据字符修剪Swift中的字符串

I would like to trim this string, so that I can extract the filename, which is always preceded by an "_" (underscore). What is the best way to do this?

我想修剪这个字符串，以便我可以提取文件名，后面总是以“_”（下划线）开头。做这个的最好方式是什么？

https://s3.amazonaws.com/brewerydbapi/beer/RXI2cT/upload_FfAPfl-icon.png

I would like the result to be FfAPfl-icon.png

我希望结果是FfAPfl-icon.png

3 个解决方案

#1

You can use String method rangeOfString:

您可以使用String方法rangeOfString：

let link = "https://s3.amazonaws.com/brewerydbapi/beer/RXI2cT/upload_FfAPfl-icon.png"
if let range = link.rangeOfString("_") {
    let fileName = link.substringFromIndex(range.endIndex)
    print(fileName)  // "FfAPfl-icon.png\n"
}

Xcode 8 beta 3 • Swift 3

Xcode 8 beta 3•Swift 3

if let range = link.range(of: "_") {
    let fileName = link.substring(from: range.upperBound)
    print(fileName) // "FfAPfl-icon.png\n"
}

#2

Since it is an URL, you can get to the string via:

由于它是一个URL，您可以通过以下方式访问该字符串：

Swift version 3

Swift版本3

let url = URL(string: "https://s3.amazonaws.com/brewerydbapi/beer/RXI2cT/upload_FfAPfl-icon.png")
let component = url?.lastPathComponent?.characters.split(separator:"_").map(String.init)

print(component?.last)// Optional("FfAPfl-icon.png")

In Swift version 2.2 or 3

在Swift 2.2或3版中

let url = NSURL(string: 
let component = url?.lastPathComponent?.characters.split{$0 == "_"}.map(String.init)

print(component?.last)

#3

For swift 3.X and swift 4.0

对于swift 3.X和swift 4.0

let strUrl = "https://www.youtube.com/watch?v=HUNcbm9sLaY"

if let range = strUrl.range(of: "=") {

     let strIdentifier = strUrl.substring(from: range.upperBound)
     print("Identifier:\(strIdentifier)")


 }

#1