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Swift pattern examples for the swift, for, and guard keywords
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| import Foundation | |
| // 1. Wildcard Pattern | |
| func wildcard(a: String?) -> Bool { | |
| guard case _? = a else { return false } | |
| for case _? in [a] { | |
| return true | |
| } | |
| switch a { | |
| case _?: return true | |
| case nil: return false | |
| } | |
| } | |
| wildcard("yes") | |
| wildcard(nil) | |
| // 2. Identifier Pattern | |
| func identifier(a: Int) -> Bool { | |
| guard case 5 = a else { return false } | |
| for case 5 in [a] { | |
| return true | |
| } | |
| switch a { | |
| case 5: return true | |
| default: return false | |
| } | |
| } | |
| identifier(5) | |
| // 3. Value Binding Pattern | |
| // 4. Tuple Pattern | |
| // 5. Type Casting Pattern | |
| func valueTupleType(a: (Int, Any)) -> Bool { | |
| guard case let (x, _ as String) = a else { return false} | |
| print(x) | |
| for case let (a, _ as String) in [a] { | |
| print(a) | |
| return true | |
| } | |
| switch a { | |
| case let (a, _ as String): | |
| print(a) | |
| return true | |
| default: return false | |
| } | |
| } | |
| let u: Any = "a" | |
| let b: Any = 5 | |
| print(valueTupleType((5, u))) | |
| print(valueTupleType((5, b))) | |
| // 6. Enumeration Pattern | |
| enum Test { | |
| case T1(Int, Int) | |
| case T2(Int, Int) | |
| } | |
| func enumeration(a: Test) -> Bool { | |
| guard case .T1(_, _) = a else { return false } | |
| for case .T1(_, _) in [Test.T1(1, 2)] { | |
| return true | |
| } | |
| switch a { | |
| case .T1(_, _): return true | |
| default: return false | |
| } | |
| } | |
| enumeration(.T1(1, 2)) | |
| enumeration(.T2(1, 2)) | |
| // 7. Expression Pattern | |
| struct Soldier { | |
| let hp: Int | |
| } | |
| func ~= (pattern: Soldier, value: Soldier) -> Bool { | |
| return pattern.hp == value.hp | |
| } | |
| func expression(a: Soldier) -> Bool { | |
| guard case Soldier(hp: 10) = a else { return false } | |
| for case Soldier(hp: 10) in [a] { | |
| return true | |
| } | |
| switch a { | |
| case Soldier(hp: 10): return true | |
| default: return false | |
| } | |
| } | |
| expression(Soldier(hp: 10)) | |
| expression(Soldier(hp: 11)) |
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