如何根據字符修剪Swift中的字符串

Question

我想修剪此字符串，以便我可以提取總是以「_」（下劃線）開頭的文件名。做這個的最好方式是什麼？

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

我想結果被FfAPfl-的icon.png

Answer 1

您可以使用字符串方法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" 
} 

---

的Xcode 8的Beta 3•斯威夫特3

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

Answer 2

因爲它是一個URL，您可以通過獲取到的字符串：

斯威夫特版本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

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

print(component?.last)