更多学习资料：
- http://nshipster.cn
- http://objccn.io/
- http://arigrant.com/
- http://oncenote.com/
- https://github.com/100mango/zen
- https://github.com/oa414/objc-zen-book-cn
- https://github.com/nixzhu/dev-blog
- https://github.com/robovm/apple-ios-samples （苹果官方 Sample 代码集合）
- https://github.com/leecade/ios-dev-flow （开发流程总结）
- https://github.com/DaiYue/iOS-good-practices-in-Chinese （iOS 最佳实践）
- https://github.com/tangqiaoboy/iOSBlogCN （iOS 开发博客列表）
- https://github.com/Aufree/trip-to-iOS （iOS 学习资料整理）
- http://www.hrchen.com/2013/05/performance-with-instruments/ (iOS 性能优化）
- https://github.com/huang303513/iOS-Study-Demo
- https://github.com/seedante/iOS-Note
- https://zsisme.gitbooks.io/ios-/content/index.html（iOS Core Animation: Advanced Techniques中文译本）
编码规范
- https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CodingGuidelines/CodingGuidelines.html#//apple_ref/doc/uid/10000146-SW1
- https://github.com/raywenderlich/objective-c-style-guide
- https://github.com/github/objective-c-style-guide