在Objective-C上存储数据

Question

I would simply like to create a file that stays around after the program quits. I would like it to contain objects that I have initiated, is that possible? Or does it just have to have text in it? How can I access that file later? Also, is this done the same way on the Mac and the iPhone?

Answer 1

Take a look at Core Data or SQLite. Apple has some sample code for them, not sure about SQLite because they prefer you tou use core data.

I will direct you to this question. Adding core data to my iPhone app

Or use NSUserDefaults: Best way to save data on the iPhone

Answer 2

Yes! It's possible.

Derive your objects that you want to persist from NSCoding. On those objects, implement the initWithCoder and encodeWithCoder functions on those objects. In these functions, write all of your primitive types to the coder (or read them) using the functions here http://developer.apple.com/library/ios/#documentation/cocoa/reference/foundation/Classes/NSCoder_Class/Reference/NSCoder.html

When you want to save your file, use an NSKeyedArchiver and pass in the object you want to archive along w/ the file name.

[NSKeyedArchiver archiveRootObject:root toFile:string]; 

More examples here https://stackoverflow.com/questions/2805026/iphone-problem-in-saving-file-using-nscoding

Answer 3

I have used SQLitePersistentObjects in the past to give my Objective-C class objects an ORM-esque feel and behaviour. The objects itself translate into corresponding tables in the database, which in this case is a simple SQLite database file.

Answer 4

存档和序列化编程指南也可能很有趣。