Unbalanced calls to begin/end appearance transitions for XXXX

This problem occurs because the previous animation has not been executed and you start the next animation. You look closely for animations before you have any other action on animations.

Beginning to see this answer, I am smart is not the animation conflict? Then put the last animation (Pushviewcontroller animated:

Change to No, think good, but do not play, sink the heart to find. I finally got it.

My nav will push two consecutive forms, and the first one is not finished yet, I'm going to push the second one. Then put the first animated:no, OK.

And this bug will only appear on the real machine, the simulator will not.

Unbalanced calls to begin/end appearance transitions for XXXX