Demo
https://developer.apple.com/library/ios/samplecode/UICatalog/Listings/Objective_C_UICatalog_AAPLAlertControllerViewController_m.html#//apple_ref/doc/uid/DTS40007710-Objective_C_UICatalog_AAPLAlertControllerViewController_m-DontLinkElementID_7
http://code.cocoachina.com/detail/297183/xe5/xbc/xba/xe5/xa4/xa7/xe7/x9a/x84UIPageControl--TAPageControl/