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Swift中String字符串的操作(切割、转Character、Character转Int、String转Array、Array转String)

hoohack 2022-04-13 阅读 87
iosSwift

1.String的切割

例如:

let name: String = "zhangsan"
// 1.获取下标,从开始位置'z',往后移动一个位置,就是'h'的位置了
let subIndex = name.index(name.startIndex, offsetBy: 1)
let subIndex2 = name.index(name.startIndex, offsetBy: 4)

// 2.根据下标获取某个字符
let subStr = name[subIndex] //Character类型: h

// 3.获取中间某部分字符串
let midStr = name[subIndex...subIndex2]  // hang

// 4.获取前面某部分
let preStr = name[...subIndex] // zh

// 5.获取后面某部分
let posStr = name[subIndex...] // hangsan

吐槽,实在是太难用了,我们写个扩展吧

extension String {
    func mySubString(_ index1: Int, _ index2: Int) -> String {
        let subIndex1 = self.index(self.startIndex, offsetBy: index1)
        let subIndex2 = self.index(self.startIndex, offsetBy: index2)
        
        return String(self[subIndex1...subIndex2])
    }
    
    func getCharAt(_ index: Int) -> Character {
        let subIndex = self.index(self.startIndex, offsetBy: index)
        
        return self[subIndex]
    }
}

使用:

let name: String = "zhangsan"
let str1 = name.mySubString(0, 1)
let char1 = name.getCharAt(2)
print("char1",char1) // char1 a
print("str1",str1) // str1 zh

2.字符Character变Int

let value: UInt32 = String(subStr).unicodeScalars.first!.value

吐槽,这也太啰嗦了吧,自己写个扩展

extension Character {
    func toInt() -> Int {
        return Int(String(self).unicodeScalars.first!.value)
    }
}

使用:

let value2 = subStr.toInt()

3.String 和 Array的转换

在一些场景中,操作String,不如操作Array方便,操作完之后,再转回String

let arr = Array(name)
print(arr)

let arrStr = String(arr[0...4])
print(arrStr)
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