保存一个 NSArray [英] Saving a NSArray

问题描述

我想将 NSArray 保存为文件或可能使用用户默认值.这就是我希望做的事情.

I would like to save an NSArray either as a file or possibly use user defaults. Here's what I am hoping to do.

1. 检索已保存的 NSArray(如果有).
2. 用它做点什么.
3. 擦除保存的数据(如果有).
4. 保存 NSArray.

这可能吗，如果可以，我应该怎么做?

Is this possible, and if so how should I do this?

推荐答案

NSArray 为你提供了两种方法来做你想做的事情:initWithContentsOfFile: 和 writeToFile:atomically:

NSArray provides you with two methods to do exactly what you want: initWithContentsOfFile: and writeToFile:atomically:

一个简短的例子可能如下所示:

A short example might look like this:

//Creating a file path under iOS:
//1) Search for the app's documents directory (copy+paste from Documentation)
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
//2) Create the full file path by appending the desired file name
NSString *yourArrayFileName = [documentsDirectory stringByAppendingPathComponent:@"example.dat"];

//Load the array
NSMutableArray *yourArray = [[NSMutableArray alloc] initWithContentsOfFile: yourArrayFileName];
if(yourArray == nil)
{
    //Array file didn't exist... create a new one
    yourArray = [[NSMutableArray alloc] initWithCapacity:10];

    //Fill with default values
}
...
//Use the content
...
//Save the array
[yourArray writeToFile:yourArrayFileName atomically:YES];

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