Swift Character
Swift's character is a single character string literally, with a data type of Character.
The following example lists two character instances:
import Cocoa let char1: Character = "A" let char2: Character = "B" print("char1 的值为 \(char1)") print("char2 的值为 \(char2)")
The output of the above program execution is:
char1 的值为 A char2 的值为 B
If you want to store more characters in a constant of the Character type, the program execution will report an error, as follows:
import Cocoa // Swift 中以下赋值会报错 let char: Character = "AB" print("Value of char \(char)")
The output of the above program execution is:
error: cannot convert value of type 'String' to specified type 'Character' let char: Character = "AB"
The empty character variable
You cannot create an empty Character type variable or constant in Swift:
import Cocoa // Swift 中以下赋值会报错 let char1: Character = "" var char2: Character = "" print("char1 的值为 \(char1)") print("char2 的值为 \(char2)")
The output of the above program execution is:
error: cannot convert value of type 'String' to specified type 'Character' let char1: Character = "" ^~ error: cannot convert value of type 'String' to specified type 'Character' var char2: Character = ""
Traverse the characters in the string
Swift's String type represents a collection of Character type values for a particular sequence. Each character value represents a Unicode character.
You can get the value of each character by traversing the acters property in the string through the for-in loop:
import Cocoa for ch in "Hello".characters { print(ch) }
The output of the above program execution is:
H e l l o
String connection characters
The following example demonstrates using String's append() method to implement string connection characters:
import Cocoa var varA:String = "Hello " let varB:Character = "G" varA.append( varB ) print("varC = \(varA)")
The output of the above program execution is:
varC = Hello G