Merge pull request #2 from CocoaChina-editors/master

pr
Merge pull request #3 from CocoaChina-editors/master

导出到本地
及时保存
暂翻译到id兼容性
02

02
更新目录
Update 07Attributes.md
update 02/07
Merge pull request #68 from numbbbbb/master

update 02/07 闭包
update 02/07

闭包部分校对结束
完成初稿 Interacting with Objective-C APIs
Merge pull request #3 from CocoaChina-editors/master

同步
Preview
Merge pull request #70 from Jasonbroker/master

Jump to Preview
2-4集合类型_初译未自校
翻译完 04Migration
纠正翻译错误
类型转换（Type Casting）

类型转换（Type Casting）
Merge pull request #72 from xiehurricane/master

02-18类型转换（Type Casting）翻译完成
修改部分翻译错误