从NSUserDefaults存储和检索长数组 [英] Storing and retrieving a long array from NSUserDefaults

问题描述

如何在 NSUserDefaults 中存储长数组并检索？

How can I store a long array into NSUserDefaults and retrieve it?

look：

long *arr;
arr = new long [10];
for(int i = 0 ; i<10 ; i++)
{
arr[i] = i;
}

现在我要存储这个 arr 到 NSUserDefaults ，然后再检索

推荐答案

只能在NSUserDefaults中存储对象。所以你必须将数组转换为 NSArray 。但是，NSArrays只存储对象，所以你需要存储封装在 NSNumber 对象中的 long p>

You can only store objects in NSUserDefaults. So you have to convert the array to an NSArray. However, NSArrays also only store objects, so you need to store the long values encapsulated in an NSNumber object:

//saving
NSUserDefaults *standardDefaults = [NSUserDefaults standardUserDefaults];
NSMutableArray *arrayObj = [[NSMutableArray alloc] init];

long *arr;
arr = new long [10];

for(int i = 0 ; i<10 ; i++) {
    [arrayObj addObject:[NSNumber numberWithLong:arr[i]]];
}

[standardDefaults setObject:arrayObj forKey:@"longArray"];
[arrayObj release];


//reading
NSUserDefaults *standardDefaults = [NSUserDefaults standardUserDefaults];
NSArray *arrayObj = [standardDefaults objectForKey:@"longArray"];

long *arr;
arr = new long [10];

for(int i = 0 ; i<10 ; i++) {
    arr[i] = [(NSNumber*)[arrayObj objectAtIndex:i] longValue];
}

这篇关于从NSUserDefaults存储和检索长数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！