格式化

[ming1016]

使用标准库的格式来描述不同场景的情况可以不用去考虑由于不同地区的区别，这些在标准库里就可以自动完成了。

描述两个时间之间相差多长时间

// 计算两个时间之间相差多少时间，支持多种语言字符串
let d1 = Date().timeIntervalSince1970 - 60 * 60 * 24
let f1 = RelativeDateTimeFormatter()
f1.dateTimeStyle = .named
f1.formattingContext = .beginningOfSentence
f1.locale = Locale(identifier: "zh_Hans_CN")
let str = f1.localizedString(for: Date(timeIntervalSince1970: d1), relativeTo: Date())
print(str) // 昨天

// 简写
let str2 = Date.now.addingTimeInterval(-(60 * 60 * 24))
    .formatted(.relative(presentation: .named))
print(str2) // yesterday

描述多个事物

// 描述多个事物
let s1 = ListFormatter.localizedString(byJoining: ["冬天","春天","夏天","秋天"])
print(s1)

描述名字

// 名字
let f2 = PersonNameComponentsFormatter()
var nc1 = PersonNameComponents()
nc1.familyName = "戴"
nc1.givenName = "铭"
nc1.nickname = "铭哥"
print(f2.string(from: nc1)) // 戴铭
f2.style = .short
print(f2.string(from: nc1)) // 铭哥
f2.style = .abbreviated
print(f2.string(from: nc1)) // 戴

var nc2 = PersonNameComponents()
nc2.familyName = "Dai"
nc2.givenName = "Ming"
nc2.nickname = "Starming"
f2.style = .default
print(f2.string(from: nc2)) // Ming Dai
f2.style = .short
print(f2.string(from: nc2)) // Starming
f2.style = .abbreviated
print(f2.string(from: nc2)) // MD

// 取出名
let componets = f2.personNameComponents(from: "戴铭")
print(componets?.givenName ?? "") // 铭

描述数字

// 数字
let f3 = NumberFormatter()
f3.locale = Locale(identifier: "zh_Hans_CN")
f3.numberStyle = .currency
print(f3.string(from: 123456) ?? "") // ¥123,456.00
f3.numberStyle = .percent
print(f3.string(from: 123456) ?? "") // 12,345,600%

let n1 = 1.23456
let n1Str = n1.formatted(.number.precision(.fractionLength(3)).rounded())
print(n1Str) // 1.235

描述地址

// 地址
import Contacts

let f4 = CNPostalAddressFormatter()
let address = CNMutablePostalAddress()
address.street = "海淀区王庄路XX号院X号楼X门XXX"
address.postalCode = "100083"
address.city = "北京"
address.country = "中国"
print(f4.string(from: address))
/// 海淀区王庄路XX号院X号楼X门XXX
/// 北京 100083
/// 中国