##### What's Page Cache?
Pgae Cache store DOM elements, javascript object and other object after webkit render html document.
https://webkit.org/blog/427/webkit-page-cache-i-the-basics/
##### Do UIWebView have Page Cache ?
UIWebView have Page Cache, that is include in WebBackForwardList. BUT default page cache size in UIWebView is ZERO, that make pageCache disable.
WKWebView's pageCache is enable default, but WKWebView could NOT be hijacked by NSURLProtocol.
##### How to enable Page Cache ?
Invoke WebPreferences's _postCacheModelChangedNotification method to post the "WebPreferencesCacheModelChangedInternalNotification" notification, make Page Cache enable.
##### Problem NOT resolved ?
I hack UCWeb, find it can hold 5 PageCache in iPhone6 iOS8.4.
But use my method, just 3 page may be cached.
My blog about how to find this solution. [**http://blog.csdn.net/wadahana/article/details/50168643**]