如何在Swift 2.0中使用防护来“增强”可选的自我

小编典典

如何在Swift 2.0中使用防护来“增强”可选的自我

swift

关于如何/ 自我，有一个类似的问题，可以回答，但是我想知道如何使用“自我”而不会由于以下原因导致向右漂移：weakify``strongify``if let

Welcome to Apple Swift version 2.0 (700.0.59 700.0.72). Type :help for assistance.
  2> import Foundation
  3> class Foo {
  4.     func guardOptSelf() -> () throws -> Void {
  5.         return { [weak self] in
  6.             guard let self = self else { throw NSError(domain: "I was destroyed!", code: 1, userInfo: nil) }
  7.             self.doSomethingNonOptionalSelf()         
  8.         }
  9.     }
  10. }
repl.swift:6:19: error: pattern matching in a condition requires the 'case' keyword
            guard let self = self else { throw NSError(domain: "I was destroyed!", code: 1, userInfo: nil) }
                  ^
                  case
repl.swift:6:23: error: binary operator '~=' cannot be applied to two 'Foo?' operands
            guard let self = self else { throw NSError(domain: "I was destroyed!", code: 1, userInfo: nil) }

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2020-07-07

共1个答案

小编典典

你可以影子self; 您只需要反引号即可表明“您知道自己在做什么”。例如：

foo.doSomethingAsyncWithBar(bar) { [weak self] result in
    guard let `self` = self else { return }
    self.receivedResult(result)
}

或者，在您的示例中：

2> import Foundation
3> class Foo {
4.     func guardOptSelf() -> () throws -> Void {
5.         return { [weak self] in
6.             guard let `self` = self else { throw NSError(domain: "I was destroyed!", code: 1, userInfo: nil) }
7.             self.doSomethingNonOptionalSelf()         
8.         }
9.     }
10. }

2020-07-07