<1>创建空字符串
let str1: String = ""
let str2: String = String()
<2>创建赋初值的字符串
var str3 = "helloworld-ZJP"
var str4 = String("你好")
<3>判断字符串是否为空
if str3.isEmpty {
print("空值")
}
if str3.count == 0 {
print("空值")
}
let str1: String = ""
let str2: String = String()
var str3 = "helloworld-ZJP"
var str4 = String("你好")
if str3.isEmpty {
print("空值")
}
if str3.count == 0 {
print("空值")
}