1、Fragment的生命周期函數
onAttach、onCreate、onCreateView、onViewCreated、onActivityCreated、onStart、onResume、onPause、onStop、onDestroyView、onDestroy、onDettach
Activity的各種生命周期函數先執行，然後各個Fragment不論是不是可見與否緊接着調用同樣的生命周期函數。比如Activity的onResume，幾個Fragment的onResume緊跟着執行。
2、Activity和Fragment的生命周期函數的順序如下：
05-25 13:49:42.757 7242-7242/com.yunzhiyuan100.wish D/Linghu MainActivity.onCreate: ============MainActivity===onCreate
05-25 13:49:42.760 7242-7242/com.yunzhiyuan100.wish D/Linghu MainActivity.onStart: ============MainActivity===onStart
05-25 13:49:42.762 7242-7242/com.yunzhiyuan100.wish D/Linghu MainActivity.onResume: ============MainActivity===onResume
05-25 13:49:42.785 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onAttach: ===================HomeFragment===onAttach
05-25 13:49:42.786 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onCreate: ===================HomeFragment===onCreate
05-25 13:49:42.786 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onAttach: ===================FindFragment===onAttach
05-25 13:49:42.787 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onCreate: ===================FindFragment===onCreate
05-25 13:49:42.787 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onAttach: ===================MineFragment===onAttach
05-25 13:49:42.787 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onCreate: ===================MineFragment===onCreate
05-25 13:49:42.788 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onCreateView: ===================HomeFragment===onCreateView
05-25 13:49:42.908 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onViewCreated: ===================HomeFragment===onViewCreated
05-25 13:49:42.908 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onActivityCreated: ===================HomeFragment===onActivityCreated
05-25 13:49:42.920 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onStart: ===================HomeFragment===onStart
05-25 13:49:42.920 7242-7242/com.yunzhiyuan100.wish D/Linghu HomeFragment.onResume: ===================HomeFragment===onResume
05-25 13:49:42.921 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onCreateView: ===================FindFragment===onCreateView
05-25 13:49:42.955 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onViewCreated: ===================FindFragment===onViewCreated
05-25 13:49:42.956 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onActivityCreated: ===================FindFragment===onActivityCreated
05-25 13:49:42.956 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onCreateView: ===================MineFragment===onCreateView
05-25 13:49:43.004 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onViewCreated: ===================MineFragment===onViewCreated
05-25 13:49:43.004 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onActivityCreated: ===================MineFragment===onActivityCreated
05-25 13:49:43.005 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onStart: ===================FindFragment===onStart
05-25 13:49:43.005 7242-7242/com.yunzhiyuan100.wish D/Linghu FindFragment.onResume: ===================FindFragment===onResume
05-25 13:49:43.006 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onStart: ===================MineFragment===onStart
05-25 13:49:43.006 7242-7242/com.yunzhiyuan100.wish D/Linghu MineFragment.onResume: ===================MineFragment===onResume
MainActivity onCreate-----onStart-----onResume---------》HomeFragment onAttach------onCreate
FindFragment onAttach------onCreate
MineFragment onAttach------onCreate
HomeFragment onCreateView------onViewCreated-------onActivityCreeated---onStart-----onResume
FindFragment onCreateView------onViewCreated--------onActivityCreated
MineFragment onCreateView-------onViewCreated-------onActivityCreated
FindFragment onStart-------onResume
MineFragment onStart-------onResume
Activity 生命周期走到可見，然後依次執行Fragment的onAttach----onCreate， 然後依次onCreateView、onViewCreated、onActivityCreated，第一個Fragment的onstart、onResume一起執行了，然後最後是後兩個Fragment的onStart、onResume。
2、下面是加入了setUserVisibleHint
Activity和Fragment的生命周期函數的順序如下：
MainActivity onCreate-----onStart-----onResume-------------》 HomeFragment setUserVisibleHint（false）
FindFragment setUserVisibleHint（false）
MineFragment setUserVisibleHint（false）
HomeFragment setUserVisibleHint（true）
HomeFragment onAttach------onCreate
切換tab，點選FindFagment
HomeFragment setUserVisibleHint（false）
FindFragment setUserVisibleHint（true）
切換tab，點選MineFragment
FindFragment===setUserVisibleHint（false）
MineFragment===setUserVisibleHint（true）
log如下：
05-25 14:11:09.453 8685-8685/com.yunzhiyuan100.wish D/Linghu MainActivity.onCreate: ============MainActivity===onCreate
05-25 14:11:09.454 8685-8685/com.yunzhiyuan100.wish D/Linghu MainActivity.onStart: ============MainActivity===onStart
05-25 14:11:09.456 8685-8685/com.yunzhiyuan100.wish D/Linghu MainActivity.onResume: ============MainActivity===onResume
05-25 14:11:09.481 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.setUserVisibleHint: ===================HomeFragment===setUserVisibleHint(false)
05-25 14:11:09.482 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.setUserVisibleHint: ===================FindFragment===setUserVisibleHint(false)
05-25 14:11:09.482 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.setUserVisibleHint: ===================MineFragment===setUserVisibleHint(false)
05-25 14:11:09.483 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.setUserVisibleHint: ===================HomeFragment===setUserVisibleHint(true)
05-25 14:11:09.484 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onAttach: ===================HomeFragment===onAttach
05-25 14:11:09.484 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onCreate: ===================HomeFragment===onCreate
05-25 14:11:09.484 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onAttach: ===================FindFragment===onAttach
05-25 14:11:09.485 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onCreate: ===================FindFragment===onCreate
05-25 14:11:09.485 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onAttach: ===================MineFragment===onAttach
05-25 14:11:09.486 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onCreate: ===================MineFragment===onCreate
05-25 14:11:09.486 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onCreateView: ===================HomeFragment===onCreateView
05-25 14:11:09.609 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onViewCreated: ===================HomeFragment===onViewCreated
05-25 14:11:09.609 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onActivityCreated: ===================HomeFragment===onActivityCreated
05-25 14:11:09.615 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onStart: ===================HomeFragment===onStart
05-25 14:11:09.615 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.onResume: ===================HomeFragment===onResume
05-25 14:11:09.616 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onCreateView: ===================FindFragment===onCreateView
05-25 14:11:09.646 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onViewCreated: ===================FindFragment===onViewCreated
05-25 14:11:09.646 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onActivityCreated: ===================FindFragment===onActivityCreated
05-25 14:11:09.646 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onCreateView: ===================MineFragment===onCreateView
05-25 14:11:09.695 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onViewCreated: ===================MineFragment===onViewCreated
05-25 14:11:09.695 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onActivityCreated: ===================MineFragment===onActivityCreated
05-25 14:11:09.695 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onStart: ===================FindFragment===onStart
05-25 14:11:09.696 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.onResume: ===================FindFragment===onResume
05-25 14:11:09.696 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onStart: ===================MineFragment===onStart
05-25 14:11:09.696 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.onResume: ===================MineFragment===onResume
點選切換到FindFragment（第二個tab）
05-25 14:13:46.807 8685-8685/com.yunzhiyuan100.wish D/Linghu HomeFragment.setUserVisibleHint: ===================HomeFragment===setUserVisibleHint(false)
05-25 14:13:46.808 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.setUserVisibleHint: ===================FindFragment===setUserVisibleHint(true)
點選切換到MineFragment（第三個tab）
05-25 14:13:48.659 8685-8685/com.yunzhiyuan100.wish D/Linghu FindFragment.setUserVisibleHint: ===================FindFragment===setUserVisibleHint(false)
05-25 14:13:48.660 8685-8685/com.yunzhiyuan100.wish D/Linghu MineFragment.setUserVisibleHint: ===================MineFragment===setUserVisibleHint(true)
3、總結：
Activity 生命周期走到可見，然後先執行Fragment的setUserVisibleHint(false)并把第一個Fragment置setUserVisibleHint(true)， 然後依次執行Fragment的onAttach----onCreate， 然後依次onCreateView、onViewCreated、onActivityCreated，第一個Fragment的onstart、onResume一起執行了，然後最後是後兩個Fragment的onStart、onResume.
Fragment的setUserVisibleHint（）執行會在onAttach方法前面。
如果點選切換Fragment的時候會調用切換兩個Fragment的setUserVisibleHint(false-----true)。
Fragment的OnResume方法和Activity的OnResume方法是調用時機是一緻。