相关疑难解决方法(0)

在Xcode8 beta6中,以下代码将引发警告:'is'test始终为true.但它不会打印通过.

    struct TestStruct {
    }

    //warning: 'is' test is always true
    if TestStruct() is AnyObject {
        print("pass")
    }

以下代码将引发警告:从'T'到'AnyObject'的条件转换始终成功

public static func register<T>(_ protocolType: T.Type, observer: T) {

    //Warning: Conditional cast from 'T' to 'AnyObject' always succeeds
    guard let object = observer as? AnyObject else {
        fatalError("expecting reference type but found value type: \(observer)")
    }
    //...
}