1、iPad上Present imagePicker失效的问题

dispatch_async(dispatch_get_main_queue(), ^ {      

    [self presentViewController:imagePickerController animated:YES completion:nil];

});

作者：YoRuo_

链接：https://www.jianshu.com/p/92ce67684941

來源：简书

2、self.navigationController.hidesBarsOnSwipe = YES

// 由于设置self.navigationController.hidesBarsOnSwipe = YES;之后，在滑动隐藏navigationBar之后返回时会有内存泄漏，所以使用UIScrollViewDelegate的方法，来进行navigationBar的隐藏与展示。

- (void)scrollViewDidScroll:(UIScrollView*)scrollView {

    CGFloaty Velocity = [scrollView.panGestureRecognizer velocityInView:scrollView].y;

    if (yVelocity > 0 && !self.statusBarAnimationInProgress) {

        [self setNavigationBarHidden:NO];

    } else if (yVelocity <0&& !self.statusBarAnimationInProgress) {

        [self setNavigationBarHidden:YES];

    }

}

- (void)setNavigationBarHidden:(BOOL)hidden {

    [CATransaction begin];

    self.statusBarAnimationInProgress = YES;

    [CATransaction setCompletionBlock:^{

        self.statusBarAnimationInProgress = NO;

    }];

    [self.navigationController setNavigationBarHidden:hidden animated:YES];

    [CATransaction commit];

}