在task.IsCompleted中准备就绪后，应立即获取该值：

FirebaseDatabase.DefaultInstance.GetReference("Values")
.GetValueAsync().ContinueWithOnMainThread(task => {

if (task.IsFaulted) {
// Handle the error...
}

else if (task.IsCompleted) {

//get the data here:

//this is snapshot of the reference
DataSnapshot snapshot = task.Result;

//this is your boolean, you get it from the snapshot
bool updateIsReady = snapshot.Child("updateIsReady").Value;

}
});