How to determine whether the ViewController has completed the jump in the IOS KIF test case?

In the IOS test case, after I tap the button I use CFRunLoopRunInMode(mode, 3, false) to wait for the UI changes(a new ViewController will appear), and then I tap the item in new ViewController. The question is the 2nd ViewController sometimes can not appear in 3s, and I want to determine the exact loading time of ViewController then I will continue to run the case immediately.

The test case like below:

[btn tap];
CFRunLoopRunInMode(mode, 3, false);
[btn2 tap];// if ViewController not loaded at this time then will crash there

Possible solution:

1. Polling
   Use a loop to determine whether a view controller is loaded.

[btn tap];
fullfilled = NO;
while(!fullfilled){
    CFRunLoopRunInMode(mode, 0.3, false);
    fullfilled = determineControllerMethod("viewControllerName");
}
[btn2 tap];

2. XCTestExpectation
   It can only use in test case while I also want to determine in normal NSObject method. XCTestExpectation can only fail with a timeout.

Are there other good methods worth to try? Thank you a lot if you can put some tips here.