坑

// self.navigationController.navigationBar.barTintColor = MAINCOLOR;
// [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:(UIBarMetricsDefault)];
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageWithColor:MAINCOLOR] forBarMetrics:(UIBarMetricsDefault)];

// self.navigationController.navigationBar.clipsToBounds = YES;//为了去一条线，引入的statubar白边