如何将用户定义的类对象的NSMutableArray存储到iPhone中的文件系统？

Question

Can anyone please tell me how to write NSMutableArray of custom class objects to file? below is the code which i am using to write my array "medicationsArray" to file. medicationsArray contains the objects of below medicationData class

@interface medicationData: NSObject { NSString *drName; NSString *date; NSString *description; } @end

NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentDir = [path objectAtIndex:0];
NSString *pathWithFileName;

NSString *pathWithFileName = [NSString stringWithFormat:@"%@/medicationsArray",documentDir];
[medicationsArray writeToFile:pathWithFileName atomically:NO];

by using this code i am not able to create a file. can anyone help me in this, thanks in advance

Answer 1

Instead of constructing the pathWithFileName "manually" you should use the stringByAppendingPathComponent: method instead:

NSString *pathWithFileName = [documentDir stringByAppendingPathComponent:@"medicationsArray"];

This will take care of any extra slashes, etc. in the path. This might be the reason your path may be wrong. I presume that the extra declaration of pathWithFileName in your snippet is just a typo.

Answer 2

Thank you for the reply Claus, Now i am able to store the data, i am using NSArchiver and NSUnArchiver. below is the code please find.

NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentDir = [path objectAtIndex:0];
NSString *pathWithFileName;

pathWithFileName = [NSString stringWithFormat:@"%@/medicationsArray",documentDir];
NSData *savedData = [NSKeyedArchiver archivedDataWithRootObject:appDelegate.medicationsArray];
[savedData writeToFile:pathWithFileName atomically:YES];

to extract the data

if([[NSFileManager defaultManager] fileExistsAtPath:pathWithFileName])
{
    NSData *savedData = [[NSData dataWithContentsOfFile:pathWithFileName] retain];
    appDelegate.medicationsArray = [[NSKeyedUnarchiver unarchiveObjectWithData:savedData] retain];
    [objMedicationDetailsTVController.tableView reloadData];
}