Question

I’m writing to and reading from a plist in my document directory. First I write the file out if there is no file found. That seemed to work correctly because at first there was no file there and now there is and double-clicking on the file shows the expected content of a key called TOSAcceptedValue with a value of NO.

But if the file is found, which happened after I ran the above once, I try to read in that same value, I’m getting a null value. Here’s the code, it may not be pretty as I’ve been hacking at it for a while to get it to function.

NSError *error;
NSString *TOSAcceptedStatus ;

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSLog( @"paths is %@", paths);

NSString *documentsDirectory = [paths objectAtIndex:0]; 
NSString *path = [documentsDirectory stringByAppendingPathComponent:@"AppUsage.plist"];

NSFileManager *fileManager = [NSFileManager defaultManager];

//first see if file exists. if it doesn't then write it out with a value of NO for Terms of Use Accepted
if (![fileManager fileExistsAtPath: path])
{                
    NSMutableDictionary *appUsageNo = [[NSMutableDictionary alloc] initWithContentsOfFile: path];

    //here add element to data file and write data to file
    NSString *value = @"NO";

    [appUsageNo setObject:@"TOSAcceptedValue" forKey:value];

    [appUsageNo writeToFile: path atomically:YES];
    [appUsageNo release]; 

    //and set TOSAcceptedStatus to no since we know its a no right now
    TOSAcceptedStatus = @"NO";

}
else { //file was found at expected location so let's see if they accepted Terms of Use already

    NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] initWithContentsOfFile: path];
    NSLog( @"path is %@", path);

    TOSAcceptedStatus = [dictionary objectForKey:@"TOSAcceptedValue"];
    //NSLog(@"TOSAcceptedStatus is %@", TOSAcceptedStatus);
    NSLog(@"TOSAcceptedStatus is %@", [dictionary objectForKey:@"TOSAcceptedValue"]);

    [dictionary release];
}

and here’s my Console results

2011-09-09 21:47:23.177 myApp[1027:207] paths is (
    "/Users/user1/Library/Application Support/iPhone Simulator/4.3/Applications/34562D85-DBE9-4A4F-A142-JEFC1F4808D1/Documents"
)
2011-09-09 21:47:44.915 myApp[1027:207] path is /Users/user1/Library/Application Support/iPhone Simulator/4.3/Applications/34562D85-DBE9-4A4F-A142-JEFC1F4808D1/Documents/AppUsage.plist
2011-09-09 21:47:50.448 myApp[1027:207] TOSAcceptedStatus is (null)

Any clues why I can’t get TOSAcceptedStatus back?

Also, am I allowed to write to and read from a plist after app started?

Answer 1

I think your main problem is that you have the object and key backwards:

[appUsageNo setObject:value forKey:@"TOSAcceptedValue"];