访问变量输出完成块

Question

我如何访问完成块之外的员工值，以便在ViewController任何地方使用它

extension TabsParentViewController{
    class func checkCreateTabPermission(completion: @escaping PermCompletionWithCancel){
        RRS.s.permissionService.checkForPermission(.createTab, completion: { (pass, employee, cancel) in
            if !cancel {
                ActivityLogsBuilder.logActivity(forEmployee: employee, module: .tabs, action: ActivityLogsBuilder.action(from: LogAction.createTab, authorized: pass))
            }
            completion(pass, employee, cancel)
        })
    }
}

Answer 1

默认情况下，调用checkCreateTabPermission为：

checkCreateTabPermission { pass, employee, cancel in
    // here you can use the `employee`
}

应该使您能够访问返回的employee 。 因此，您可以在checkCreateTabPermission的completion中调用所需的方法：

checkCreateTabPermission { pass, employee, cancel in
    myMethod(employee: employee)
}

或者，如果您想在completion之外访问员工，您可以声明一个变量（默认情况下为nil ）以在返回后保存其值：

var myEmployee: Employee?

checkCreateTabPermission { [weak self] pass, employee, cancel in
    self?.myEmployee = employee
}

// you could use `myEmployee` here, but you have to make sure its not nil,
// in other words, `checkCreateTabPermission` has been called and retrieved one.
if let myUnwrappedEmployee = myEmployee {
    // use `myUnwrappedEmployee`...
}