在读一些 Swift 的框架源码时，会发现一些简洁的 Api，本文用来记录这些代码片段，以后开发中可能会用到。
判断是否可以导入某个库
#if canImport(SpriteKit)
// this will be true for iOS, macOS, tvOS, and watchOS
#else
// this will be true for other platforms, such as Linux
#endif
判断是否为模拟器
#if targetEnvironment(simulator)
// code for the simulator here
#else
// code for real devices here
#endif
条件编译
#if !os(Linux)
// Matches macOS, iOS, watchOS, tvOS, and any other future platforms
#endif
#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
// Matches only Apple platforms, but needs to be kept up to date as new platforms are added
#endif
让 Xcode 在编译时候作出提示
func encrypt(_ string: String, with password: String) -> String {
#warning("This is terrible method of encryption")
return password + String(string.reversed()) + password
}
struct Configuration {
var apiKey: String {
#error("Please enter your API key below then delete this line.")
return "Enter your key here"
}
}
#if os(macOS)
#error("MyLibrary is not supported on macOS.")
#endif
使用 Raw 字符串
使用#来包裹的 Raw 字符串，里面的字符不会做处理，特别是一些转义字符。对于正则的特别好用:
let regex1 = "\\\\[A-Z]+[A-Za-z]+\\.[a-z]+"
let regex2 = #"\\[A-Z]+[A-Za-z]+\.[a-z]+"#
插值需要这样做:
let answer = 42
let dontpanic = #"The answer is \#(answer)."#
使用多个 # 号来消除歧义，前后 # 号数量要一致：
let a = ##"aaa"#"##
print(a) // aaa"#
跨越多行的字符串可以使用"""来包裹。
let quotation =
"""
The White Rabbit put on his spectacles. "Where shall I begin,
please your Majesty?" he asked.
"Begin at the beginning," the King said gravely, "and go on
till you come to the end; then stop."
"""
文档信息
- 本文作者：Ning Zhang
- 本文链接：https://sunsetroads.github.io/2018/08/27/swift-tips/
- 版权声明：自由转载-非商用-非衍生-保持署名（创意共享3.0许可证）