使用iTeardownMyAppFrame和iStartMyAppInAFrame在OPA5测试中重新启动应用程序超时(Restart app within OPA5 test using iTeardownMyAppFrame and iStartMyAppInAFrame timed out)

 tl; dr：Firebase提供的setValue(_ value: Any?, andPriority priority: Any?)与使用setValue(_ value: Any?, withCompletionBlock: (Error?, FIRDatabaseReference) -> Void) 。 
 
 解决方案 ：使用具有多种类型的API时，请避免使用尾随封闭。 在这种情况下，首选setValue(myValue, withCompletionBlock: { (error, dbref) in /* ... */ }) ; 请勿setValue(myValue) { (error, dbref) in /* ... */ }使用setValue(myValue) { (error, dbref) in /* ... */ } 。 
 
 说明 
 
 这似乎是一个Swift错误。 和其他语言一样，Swift通常会选择最具体的过载。 例如， 
 
class Alpha {}
class Beta : Alpha {}

class Charlie {
    func charlie(a: Alpha) {
        print("\(#function)Alpha")
    }
    func charlie(a: Beta) {
        print("\(#function)Beta")
    }
}

Charlie().charlie(a: Alpha()) // outputs: charlie(a:)Alpha
Charlie().charlie(a: Beta() as Alpha) // outputs: charlie(a:)Alpha
Charlie().charlie(a: Beta()) // outputs: charlie(a:)Beta
 
 但是，当重载函数匹配尾随闭包时，Swift（至少有时）会选择更一般的类型。 例如， 
 
class Foo {
    func foo(completion: () -> Void) {
        print(#function)
    }
    func foo(any: Any?) {
        print(#function)
    }
}

func bar() {}
Foo().foo(completion: bar) // outputs: foo(completion:)
Foo().foo(any: bar) // outputs: foo(any:)
Foo().foo() { () in } // outputs: foo(any:)
// ^---- Here lies the problem
// Foo().foo(bar) will not compile; can't choose between overrides.
 
 Any? 是比() -> Void更普遍的类型 - 即“任何东西，甚至是空”比“接收0个参数并返回Void类型的东西的函数”更广泛。 但是，追尾的关闭匹配Any? ; 这与您所期望的与最具体类型匹配的语言相反。 

tl;dr: Firebase provides a setValue(_ value: Any?, andPriority priority: Any?) which is incorrectly matched when using a trailing closure with setValue(_ value: Any?, withCompletionBlock: (Error?, FIRDatabaseReference) -> Void).
 
Solution: When using an API that has many varieties, avoid using trailing closures. In this case, prefer setValue(myValue, withCompletionBlock: { (error, dbref) in /* ... */ }); do not use setValue(myValue) { (error, dbref) in /* ... */ }.
 
Explanation
 
This appears to be a Swift bug. As in other languages, such as Java, Swift generally chooses the most specific overload. E.g.,
 
class Alpha {}
class Beta : Alpha {}

class Charlie {
    func charlie(a: Alpha) {
        print("\(#function)Alpha")
    }
    func charlie(a: Beta) {
        print("\(#function)Beta")
    }
}

Charlie().charlie(a: Alpha()) // outputs: charlie(a:)Alpha
Charlie().charlie(a: Beta() as Alpha) // outputs: charlie(a:)Alpha
Charlie().charlie(a: Beta()) // outputs: charlie(a:)Beta
 
However, when overloaded functions match a trailing closure, Swift (at least, sometimes) selects the more general type. E.g.,
 
class Foo {
    func foo(completion: () -> Void) {
        print(#function)
    }
    func foo(any: Any?) {
        print(#function)
    }
}

func bar() {}
Foo().foo(completion: bar) // outputs: foo(completion:)
Foo().foo(any: bar) // outputs: foo(any:)
Foo().foo() { () in } // outputs: foo(any:)
// ^---- Here lies the problem
// Foo().foo(bar) will not compile; can't choose between overrides.
 
Any? is a more general type than () -> Void -- i.e., "anything, even null" is more broad than "a function receiving 0 parameters and returning something of type Void". However, the trailing closure matches Any?; this is the opposite of what you would expect from a language that matches the most specific type.