在animate中reloadData是相当错误的，会引起变得缓慢！！
[UIView animateWithDuration:0 animations:^{
NSLog(@"lml-info-vc-test-net-animations-reloadData-bigin");
[self.pre_tableView reloadData];
NSLog(@"lml-info-vc-test-net-animations-reloadData-end");
} completion:^(BOOL finished) {
//Do something after that...
[_pre_tableView.mj_footer endRefreshing];
[_pre_tableView.mj_header endRefreshing];
}];
官方文档明确说了不能在animate中reloadData：
https://developer.apple.com/reference/uikit/uitableview/1614862-reloaddata?language=objc
Discussion
Call this method to reload all the data that is used to construct the table, including cells, section headers and footers, index arrays, and so on. For efficiency, the table view redisplays only those rows that are visible. It adjusts offsets if the table shrinks as a result of the reload. The table view’s delegate or data source calls this method when it wants the table view to completely reload its data. It should not be called in the methods that insert or delete rows, especially within an animation block implemented with calls to beginUpdates and endUpdates.
