折腾了半天，各种百度，都是说在html的video中加入webkit-playsinline属性，可是怎么都不起作用，后来去Apple查看官方API，人家已经说的很明白了，真是一顿头大啊。
You must set this property to play inline video. Set this property to true to play videos inline. Set this property to false to use the native full-screen controller. When adding a video element to a HTML document on the iPhone, you must also include the playsinline attribute.
Important
Apps created before iOS 10.0 must use the webkit-playsinline attribute.
不废话了，直接上代码
CGFloat phoneVersion = [[[UIDevice currentDevice] systemVersion] floatValue];
if (phoneVersion >= 10.0) {
content = [content stringByReplacingOccurrencesOfString:@"<video" withString:@"<video playsinline"];
}else {
content = [content stringByReplacingOccurrencesOfString:@"<video" withString:@"<video webkit-playsinline"];
}
最后别忘了设置webView的allowsInlineMediaPlayback属性为YES
webView.allowsInlineMediaPlayback = YES;
