全文转载整理自互联网,感谢原作者。

其实只需要一行CSS代码

-webkit-overflow-scrolling : touch;

实际上Safari真的用了原生控件来实现,对于有-webkit-overflow-scrolling的网页,会创建一个UIScrollView提供子layer给渲染模块使用。创建时的堆栈如下:

Thread 1, Queue : com.apple.main-thread
#0    0x00086723 in -[UIScrollView initWithFrame:] ()
#1    0x004ec3bd in -[UIWebOverflowScrollView initWithLayer:node:webDocumentView:] ()
#2    0x001f1769 in -[UIWebDocumentView webView:didCreateOrUpdateScrollingLayer:withContentsLayer:scrollSize:forNode:allowHorizontalScrollbar:allowVerticalScrollbar:] ()
#3    0x01d571bd in __invoking___ ()
#4    0x01d570d6 in -[NSInvocation invoke] ()
#5    0x01d5724a in -[NSInvocation invokeWithTarget:] ()
#6    0x027fb6a1 in -[_WebSafeForwarder forwardInvocation:] ()
#7    0x027fb8ab in __44-[_WebSafeAsyncForwarder forwardInvocation:]_block_invoke_0 ()
#8    0x04ac753f in _dispatch_call_block_and_release ()
#9    0x04ad9014 in _dispatch_client_callout ()
#10    0x04ac97d5 in _dispatch_main_queue_callback_4CF ()
#11    0x01d09af5 in __CFRunLoopRun ()
#12    0x01d08f44 in CFRunLoopRunSpecific ()
#13    0x01d08e1b in CFRunLoopRunInMode ()
#14    0x01cbd7e3 in GSEventRunModal ()
#15    0x01cbd668 in GSEventRun ()
#16    0x00032ffc in UIApplicationMain ()
#17    0x00002ae2 in main at /Users/liuhx/Desktop/UIWebView_Research/WebViewResearch/main.mm:16

实际创建的是UIWebOverflowScrollView,它继承自UIScrollView,声明为:

@class DOMNode, UIWebDocumentView, UIWebOverflowContentView, UIWebOverflowScrollListener;

@interface UIWebOverflowScrollView : UIScrollView
{
    UIWebDocumentView *_webDocumentView;
    UIWebOverflowScrollListener *_scrollListener;
    UIWebOverflowContentView *_overflowContentView;
    DOMNode *_node;
    BOOL _beingRemoved;
}

@property(nonatomic, getter=isBeingRemoved) BOOL beingRemoved; // @synthesize beingRemoved=_beingRemoved;
@property(retain, nonatomic) DOMNode *node; // @synthesize node=_node;
@property(retain, nonatomic) UIWebOverflowContentView *overflowContentView; // @synthesize overflowContentView=_overflowContentView;
@property(retain, nonatomic) UIWebOverflowScrollListener *scrollListener; // @synthesize scrollListener=_scrollListener;
@property(nonatomic) UIWebDocumentView *webDocumentView; // @synthesize webDocumentView=_webDocumentView;
- (void)setContentOffset:(struct CGPoint)arg1;
- (void)_replaceLayer:(id)arg1;
- (void)prepareForRemoval;
- (void)fixUpViewAfterInsertion;
- (id)superview;
- (void)dealloc;
- (id)initWithLayer:(id)arg1 node:(id)arg2 webDocumentView:(id)arg3;

@end

其还有一个子View作为ContentView,是给WebCore真正用作渲染overflow型内容的layer的容器。

UIWebOverflowContentView的声明为:

@interface UIWebOverflowContentView : UIView
{
}

- (void)_setCachedSubviews:(id)arg1;
- (void)_replaceLayer:(id)arg1;
- (void)fixUpViewAfterInsertion;
- (id)superview;
- (id)initWithLayer:(id)arg1;

@end

再往底层跟,都是CALayer的操作。

以上两个类都是UIKit层的实现,需要WebCore有硬件加速的支持才有实际意义,相关的逻辑被包含在ACCELERATED_COMPOSITING这个宏里。从SVN log看,在WebKit 108400版本左右才支持,所以iOS Safari应该是需要5.0,Android只在4.0以上支持。从前端开发的角度讲,只需要知道CSS的属性-webkit-overflow-scrolling是真的创建了带有硬件加速的系统级控件,所以效率很高。但是这相对是耗更多内存的,最好在产生了非常大面积的overflow时才应用。


data.update.lastsys.time.agopunc.commaarticle.create.bypunc.commaarticle.file.inpunc.colonCSSpunc.caesuramacOSpunc.caesuraiOS

这种格式在Safari和IOS中无法正常运行,值为NaN

var $date = new Date("2016-06-01 08:00");

需要格式改为

var $date = new Date("2016/06/01 08:00");

可以用以下正则替换

$date.replace(/\-/g, '/');

data.update.lastsys.time.agopunc.commaarticle.create.bypunc.commaarticle.file.inpunc.colonJavaScriptpunc.caesuramacOSpunc.caesuraiOS

尝试了好几种方式,都不是很完美,最后使用了以下方案,但仍有可能造成输入框弹起时即刻执行修补,导致输入框覆盖了被输入对象的情况,不过基本都解决了,蛮好的。

document.body.addEventListener('focusout', () => {
            //软键盘收起的事件处理
            let ua = window.navigator.userAgent;
            let app = window.navigator.appVersion;
            //console.log('浏览器版本: ' + app + '\n' + '用户代理: ' + ua);
            if (!!ua.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/)) {
                console.log('ios端');
                var currentPosition, timer;
                var speed = 1;
                //为了防止快速input切换导致闪屏,间隔100毫秒执行
                timer = setInterval(function () {
                    currentPosition = document.documentElement.scrollTop || document.body.scrollTop;
                    currentPosition -= speed;
                    window.scrollTo(0, currentPosition); //页面向上滚动
                    currentPosition += speed;
                    window.scrollTo(0, currentPosition); //页面向下滚动
                    clearInterval(timer);
                }, 100);
            } else if (ua.indexOf('Android') > -1 || ua.indexOf('Adr') > -1) {
                //console.log('android端');
            }
        });

data.update.lastsys.time.agopunc.commaarticle.create.bypunc.commaarticle.file.inpunc.colonJavaScriptpunc.caesuraiOS
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