1、Property Lists
屬性列表，擴(kuò)展名為plist。
- Property list有三種存儲(chǔ)方式：XML, binary format, “old-style” ASCII format inherited from OpenStep。old-style format的序列化API是只讀的。
A property list can be stored in one of three different ways: in an XML representation, in a binary format, or in an “old-style” ASCII format inherited from OpenStep. You can serialize property lists in the XML and binary formats. The serialization API with the old-style format is read-only.
- 數(shù)據(jù)大小限制（幾百kb內(nèi)）
For situations where you need to store small amounts of persistent data—say less than a few hundred kilobytes—property lists offer a uniform and convenient means of organizing, storing, and accessing the data.
In some situations, the property-list architecture may prove insufficient. If you need a way to store large, complex graphs of objects, objects not supported by the property-list architecture, or objects whose mutability settings must be retained, use archiving.
如果我們的對(duì)象全由NSDictionary, NSArray, NSString, NSDate, NSData, 或NSNumber類派生，我們可以創(chuàng)建property list。
XML property list 比 binary 格式的可移植性好，可以手動(dòng)編輯，但是binary property lists 兼容性好，需要的存儲(chǔ)空間少，讀寫速度要優(yōu)于XML property lists。通常來(lái)說(shuō)，如果你的property list相對(duì)較小，XML property lists的優(yōu)點(diǎn)會(huì)戰(zhàn)勝它相對(duì)binary property lists的I/O速度，難兼容的缺點(diǎn)。
如果你有大量數(shù)據(jù)，binary property lists, keyed archives，或自定義數(shù)據(jù)格式會(huì)是更好的解決方案。
2、NSUserDefaults
NSUserDefaults，提供了與默認(rèn)系統(tǒng)交互的程序接口。
默認(rèn)系統(tǒng)允許應(yīng)用去自定義它的行為來(lái)符合用戶的偏好。所以它主要是用來(lái)存儲(chǔ)配置信息。
支持的數(shù)據(jù)類型有：floats，doubles，integers，Booleans，URLs，NSData，NSString，NSNumber，NSDate，NSArray和NSDictionary。如果還想存儲(chǔ)其他類型的對(duì)象，需要使用NSData對(duì)它們進(jìn)行歸檔。
事實(shí)上，NSUserDefaults就是把數(shù)據(jù)保存在property list中
3、Archive
Archives provide a means to convert objects and values into an architecture-independent stream of bytes that preserves the identity of and the relationships between the objects and values.
如果對(duì)象是NSString、NSDictionary、NSArray、NSData、NSNumber等類型，可以直接用NSKeyedArchiver進(jìn)行歸檔和恢復(fù)。
不是所有的對(duì)象都可以直接用這種方法進(jìn)行歸檔，只有遵守了NSCoding協(xié)議的對(duì)象才可以。
3、DB
數(shù)據(jù)庫(kù)可以提供對(duì)數(shù)據(jù)更加高級(jí)的操作，這是其他方式不能提供的。當(dāng)涉及到建模，查詢，遍歷，持久化復(fù)雜的對(duì)象圖，就可以采用數(shù)據(jù)庫(kù)來(lái)實(shí)現(xiàn)數(shù)據(jù)持久化。
- SQLite
- Core Data
- FMDB
