Swift-Converts a number of type string to a numeric type (supports decimal, hexadecimal)

1, the decimal string into the digital swift, if you want to convert the string to a numeric type (such as Integer, floating point type, etc.). You can turn it into a nsstring type first, then turn it back.

// Convert the value in the text box to a number var i = (tf1.text as NSString) .intValue var f = (tf1.text as NSString) .floatValue var d = (tf1.text as NSString) .doubleValue

2, the hexadecimal string is converted to a number (1) to define a conversion method

func hexStringToInt (from: String)-> Int {      let str = from.uppercased ()      var sum = 0      for i in str.utf8 {          sum = sum * 16 + Int (i)-48 // 0-9 starts at 48          if i> = 65 {// A-Z starts at 65, but has an initial value of 10, so it should be minus 55              sum-= 7          }      }      return sum }

Use the sample:

let str ="FF0000" let value = hexStringToInt(from:str) print(value)

(2) can also be implemented by extending the string

extension String {      func hexStringToInt ()-> Int {          let str = self.uppercased ()          var sum = 0          for i in str.utf8 {              sum = sum * 16 + Int (i)-48 // 0-9 starts at 48              if i> = 65 {// A-Z starts at 65, but has an initial value of 10, so it should be minus 55                  sum-= 7              }          }          return sum      } }

Use the sample:

let str ="FF0000" let value = str.hexStringToInt() print(value)

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Swift-Converts a number of type string to a numeric type (supports decimal, hexadecimal)