如何在 iOS 11 中像点击状态栏一样调用缓慢滚动到顶部的动画？

Posted 2023-03-04

【中文标题】如何在 iOS 11 中像点击状态栏一样调用缓慢滚动到顶部的动画？

【英文标题】：How to invoke the slowly scroll to top animation in iOS 11 just like when tapping the status bar?

【发布时间】：2018-02-23 17:27:00

【问题描述】：

我希望用户点击标签栏项目让滚动视图滚动到顶部。

如果只是像下面这样设置内容偏移，动画与在 ios 11 中点击状态栏滚动到顶部不同。

scrollView.setContentOffset(CGPoint(x: 0, y: -scrollView.adjustedContentInset.top), animated: true)

我在App Store应用中发现，当用户点击标签栏项目时，页面会滚动到顶部，并且动画与点击状态栏相同，如何存档这个动画？

【问题讨论】：

试试scrollRectToVisible

【参考方案1】：

你可以钩住scrollView的顶部约束并且想要你想要的

self.scrollTopCon.constant = // value

UIView.animate(withDuration: 0.5, animations: 

    self.view.layoutIfNeeded()

)

【参考方案2】：

extension UIScrollView 

    @objc public func extension_scrollToTopIfPossible(animated: Bool) 
        let selector = NSSelectorFromString("_scrollToTopIfPossible:")
        guard self.responds(to: selector) else 
            return
        
        self.performSelector(onMainThread: selector, with: animated ? true : nil, waitUntilDone: true)
    


OR

@implementation UIWindow (SCROLL)

- (void)performScrollToTop 

    SEL selector = NSSelectorFromString(@"_scrollToTopViewsUnderScreenPointIfNecessary:resultHandler:");

    if ([self respondsToSelector:selector] == false) 
        return;
    

    NSMethodSignature *signature = [UIWindow instanceMethodSignatureForSelector:selector];

    if (signature == nil) 
        return;
    

    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[UIWindow instanceMethodSignatureForSelector:selector]];

    [invocation setTarget:self];

    [invocation setSelector:selector];

    CGRect statusBarFrame = UIApplication.sharedApplication.statusBarFrame;

    CGPoint point = CGPointMake(statusBarFrame.size.width / 2.0, statusBarFrame.size.height + 1.0);

    [invocation setArgument:&point atIndex:2];

    [invocation invoke];


@end

【讨论】：

请将您的代码格式化为代码，并为您的代码添加一些解释