Merge pull request #14 from xiatao123/master

added the categories
tiny changes
Merge branch 'master' into linkai_search
set global category
code clean
add global cache v1.0
Merge pull request #15 from ios-class/linkai_search

Linkai search
add global cache v2
Merge pull request #16 from ios-class/linkai_search

add global cache v2
add global cache v3
Merge pull request #17 from ios-class/linkai_search

add global cache v3