摘自apple文檔：
The SDK version, not the deployment target, determines which features you can use in an app. If the SDK you’re using to build the app is more recent than the app’s deployment target, Xcode displays build warnings when it detects that your app is using a feature that’s unavailable in the deployment target顾翼。
SDK的版本（并不是程序的部署目標(biāo)）玖院，它決定了你可以在你的app中使用的特性。如果你用來(lái)構(gòu)建app的SDK版本比得app的部署目標(biāo)版本更新雇逞，那么當(dāng)Xcode檢測(cè)到你的app使用的特性在部署目標(biāo)版本中并不可用時(shí)劣摇，它就會(huì)顯示編譯警告珠移。
摘自apple文檔：
About Info.plist Keys and Values
To provide a better experience for users, iOS and OS X rely on the presence of special metadata in each app or bundle. This metadata is used in many different ways. Some of it is displayed to the user, some of it is used internally by the system to identify your app and the document types it supports, and some of it is used by the system frameworks to facilitate the launch of apps. The way an app provides its metadata to the system is through the use of a special file called an information property list file, or Info.plist for short.
A property list is a way to structure arbitrary data that the system can access at runtime. An information property list is a specialized type of property list that contains configuration data for a bundle. The keys and values in the file describe the various behaviors and configuration options you want applied to your bundle. An Xcode project template typically specifies an information property list file with an initial set of keys and appropriate default values. You can edit the file to change or add keys and values, as appropriate for your project.
關(guān)于Info.plist 的鍵和值
為了給用戶提供一個(gè)更好的體驗(yàn)，iOS和OS X依賴于在每個(gè)app或者bundle里存在的特殊的元數(shù)據(jù)末融。這些元數(shù)據(jù)被使用許多不同的方法钧惧。其中一些展示給用戶，還有一些在系統(tǒng)內(nèi)部使用來(lái)辨別你的app和你的app支持的文件類型勾习，還有一些被系統(tǒng)框架使用來(lái)減輕app的啟動(dòng)速度浓瞪。這種app提供元數(shù)據(jù)給系統(tǒng)的方式，是通過(guò)使用一種特殊的（被稱作屬性信息列表）文件巧婶，或者簡(jiǎn)稱info.plist乾颁。
一個(gè)屬性列表是一種構(gòu)造任意數(shù)據(jù)（系統(tǒng)可以在運(yùn)行時(shí)訪問(wèn)的數(shù)據(jù)）的方式。 一個(gè)信息屬性列表是一種專業(yè)類型的屬性列表粹舵，它包括了提供給bundle的配置數(shù)據(jù)钮孵。這些在plist里的鍵值對(duì)描述了各種行為和你想應(yīng)用到bundle的配置選項(xiàng)。一個(gè)Xcode工程模板通常指定一個(gè)信息屬性列表眼滤，其中包含用來(lái)初始化設(shè)置的鍵和相應(yīng)適當(dāng)?shù)哪J(rèn)值巴席。你可以酌情根據(jù)你的工程，編輯這個(gè)文件來(lái)改變或者添加這些鍵值對(duì)诅需。
