分享一些免费接口
http://blog.csdn.net/iosdevelopers/article/details/25275599
细说 iOS 消息推送
http://www.cnblogs.com/lovewx/p/3837309.html
http://www.cocoachina.com/applenews/devnews/2014/0528/8582.html
后台服务(Background Modes in iOS Tutorial)
http://www.raywenderlich.com/29948/backgrounding-for-ios
iOS 7 Programming Pushing the Limits
http://www.cnblogs.com/yangfaxian/p/3825336.html
定制iOS 7中的导航栏和状态栏
http://www.cocoachina.com/applenews/devnews/2013/1104/7287.html
iOS7下Status Bar字体颜色修改
http://www.th7.cn/Program/IOS/201310/153822.shtml