5.Swift 字符串的小技巧

在之前我就写过一篇文章关于可以插入字符的文章23.使用Swift自带的join函数拼接字符串,这里讲的是使用join函数在每个字符之间插入自定义的字符.

1.获取字符串的索引

let sayHello = "Hello word!"

// 开始的characters字符,输出的结果为: H
print(sayHello[sayHello.startIndex])

// 结尾的characters字符,输出的结果为: !
print(sayHello[sayHello.endIndex.predecessor()])

// 第7个characters的字符,输出的结果为: o
print(sayHello[sayHello.startIndex.advancedBy(7)])

// 遍历sayHello的characters的索引范围,输出的结果为: H-e-l-l-o- -w-o-r-d-!-
for index in sayHello.characters.indices {
    // 在每个索引字符后面添加一个字符
    print("\(sayHello[index])",terminator: "-")
}

2.插入和删除字符

var welcome = "hello"

// 插入字符"!"到welcome最后的索引
welcome.insert("!",atIndex: welcome.endIndex)
print(welcome)

// 插入字符" wrod"在welcome最后的索引前一个
welcome.insertContentsOf(" word".characters,at: welcome.endIndex.predecessor())
print(welcome)

// 删除在welcome最后的索引前一个
welcome.removeAtIndex(welcome.endIndex.predecessor())

print(welcome)

// 删除规定范围内的字符
let range = welcome.endIndex.advancedBy(-5) ..< welcome.endIndex

welcome.removeRange(range)

print(welcome)

输出结果

3.判断字符

在Swift当中有分为三种对比,字符内容相等,字符后缀相等,字符后缀相等.

字符内容判断

let hello = "hello"
let hi = "hello"

if hello == hi {
    print("These two strings are considered equal")
}

字符前缀判断

let personName = [
    "person name 1 : xiaoming","person name 2 : honghong","person name 3 : zhangsan","person name 4 : lisi","person name 5 : huangwu","person name 6 : datou"
]

var personNumber = 0

for name in personName {
    if name.hasPrefix("person") {
        ++personNumber
    }
}

print(personNumber)
// 输出的结果为: 6

字符串后缀判断

let personLastName = [
    "xiaoming chen","xiaohong chen","zhangsan li","baibai chen"
]

var personLastNameNumber = 0

for lastName in personLastName {
    if lastName.hasSuffix("chen") {
        ++personLastNameNumber
    }
}

print(personLastNameNumber)
// 输出结果为: 3

好了,这次就讲到这里,谢谢