iPhone - int到NSData？

Question

我正在制作一个iPhone应用程序,我希望保存应用程序的状态.这包括一个int属性,我将自己持久保存到文件中.我有它编写和工作,但我知道我做的方式是有点hacky,将int转换为String然后转换为NSData.任何人都可以提出更好的方法吗？

int someInt = 1;
NSString *aString = [NSString stringWithFormat:@"%d",someInt];
NSData *someData = [aString dataUsingEncoding:NSUTF8StringEncoding];
[someData writeToFile:[documentsDirectory stringByAppendingString:@"someFile"] atomically:YES];

然后从磁盘读取它并将其放回int -

NSData* someData = [NSData dataWithContentsOfFile:[documentsDirectory stringByAppendingString:@"someFile"]];
NSString *aString = [[NSString alloc] initWithData:someData encoding:NSUTF8StringEncoding];
int someInt = [aString intValue];

Answer 1

来写:

int i = 1;
NSData *data = [NSData dataWithBytes: &i length: sizeof(i)];
[data writeToFile: [documentsDirectory stringByAppendingString: @"someFile"] atomically: YES]

并回读:

NSData *data = [NSData dataWithContentsOfFile: [documentsDirectory stringByAppendingString: @"someFile"]];
int i;
[data getBytes: &i length: sizeof(i)];

但是,你真的应该使用这样NSUserDefaults的东西,在这种情况下你会做:

[[NSUserDefaults standardUserDefaults] setInteger: i forKey: @"someKey"]

写,和

int i = [[NSUserDefaults standardUserDefaults] integerForKey: @"someKey"];

阅读.