swift_tips.md

Swift

null check

• https://stackoverflow.com/questions/54966200/does-swift-have-standard-scope-functions-like-in-kotlin

extension

extension Optional {
    func `let`(do: (Wrapped)->()) {
        guard let v = self else { return }
        `do`(v)
    }
}

var str: String? = "text"
str.let {
    print( $0 ) // prints `text`
}
str = nil

str.let {
    print( $0 ) // not executed if str == nil
}

map

// prints 123
let str1 : String? = "123"
str1.map { print($0) }

// doesn't print anything
let str2 : String? = nil
str2.map { print($0) }

idiomatic

var str: String? = "123"
if let s = str { 
    print(s) 
}

let str2: String? = "123"
guard let strUnwrapped = str2 else { return }

xcode_shortcuts.md

• jump to Definition: Ctrl + Command + J
• back and forward: Ctrl + Command + Forward Arrow or Ctrl + Command + Back Arrow
• auto fix next error: Ctrl + Cmd + '
• auto fix prev error: Ctrl + Cmd + "
• fix XCode odd errors: https://github.com/codepath/ios_guides/wiki/Fixing-Xcode