stringByAddingPercentEscapesUsingEncoding（NSUTF8StringEncoding）在Swift中返回Optional

我正在尝试使用Swift解决以下问题：

1）可选？ 为什么下面的代码返回“1％20Market％20Street，％20San％20Francisco，％20CA％2094107” “）”

println("\(address.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding))") 

2）如何用％2Creplace逗号？

Answer 1

1）

使用任一

 println("\(address.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!)") 

注意! – 它提取可选值。

要么

 if let str = address.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding) { println(str) } 

2）

你可以使用像这样的东西：

 let stringWithCommas = "Hello,World" let stringWithReplacedCommas = stringWithCommas.stringByReplacingOccurrencesOfString(",", withString: "%2C", options: NSStringCompareOptions.LiteralSearch, range: nil) 

Answer 2

你可以使用这个

  let tempString: String? = "1%20Market%20Street,%20San%20Francisco,%20CA%2094107" if tempString != nil { let newString = tempString!.stringByReplacingOccurrencesOfString(",", withString: "%2C", options: NSStringCompareOptions.LiteralSearch, range: nil) } 

它返回可选项，因为有时这个方法返回nil。

Answer 3

1.是返回可选值，因为它可以返回在Swift中可选的nil值来详细了解可选值

 var newString = String() if let optionalString = newString.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding) { newString = "1%20Market%20Street,%20San%20Francisco,%20CA%2094107" } // 2. To replace , with %2C newString.stringByReplacingOccurrencesOfString(",", withString: "%2C", options: NSStringCompareOptions.LiteralSearch, range: nil)