What events come, call the relevant function handle, very convenient for use in the library functions as a writer to provide a callback interface, and then call the library's do the relevant event handling and status acquisition, writers libraries to shield the relevant information , library users require more flexible permissions, involving two people to use.
static xxxxxxxxxxxxx(，，callback）
{
if(xxx) {
callback
}
if(xxx) {
callback
}
}
static xxxx()
{
// What is the status information or own their own business event processing logic processing
}