How to write data in plist?

Question

I have created save.plist in a resource folder. I have written some data within that directly (without using coding). I am able to read that data but I'm not able to write through code to the same save.plist. By using following code I am trying to write the data but it gets stored within my .app plist. The code is here

NSString *errorDesc = nil;

NSPropertyListFormat format;

NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"save" ofType:@"plist"];

NSData *plistXML = [[NSFileManager defaultManager] contentsAtPath:plistPath];

NSMutableDictionary *temp = (NSMutableDictionary *)[NSPropertyListSerialization
                     propertyListFromData:plistXML
                              mutabilityOption:NSPropertyListMutableContainersAndLeaves
                  format:&format errorDescription:&errorDesc];

if (!temp) {

    NSLog(errorDesc);

    [errorDesc release];        
    }
    //  [temp setValue:@"123" forKey:@"line1"];
    //  [temp writeToFile:plistPath atomically: YES];

    //Reading data from save.plist
    NSLog([temp objectForKey:@"name"]);
    NSLog([temp objectForKey:@"wish"]);
    NSNumber *num=[temp valueForKey:@"roll"];
    int i=[num intValue];
    printf("%d",i);
        //writitng the data in save.plist

    [temp setValue:@"green" forKey:@"color"];
    [temp writeToFile:plistPath atomically: NO];
    NSMutableDictionary *temp1 = (NSMutableDictionary *)[NSPropertyListSerialization
                propertyListFromData:plistXML                                                            
                                mutabilityOption:NSPropertyListMutableContainersAndLeaves
                format:&format errorDescription:&errorDesc];

    NSLog([temp objectForKey:@"color"]);

I want that, the data which I want to write should get written into save.plist only which is stored in references. I am new with this concept. So if anyone knows it please help me. Thanks in advance. :-)

Answer 1

I don't know if I understand your question, but if you want to write into a .plist within your .app bundle you are probably doing something wrong. If you want to store preferences, you should consider using NSUserDefaults.
If you really want to modify a bundled .plist - here is some code:

NSString *plistPath = nil;
NSFileManager *manager = [NSFileManager defaultManager];
if (plistPath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:@"Contents/Info.plist"]) 
{
    if ([manager isWritableFileAtPath:plistPath]) 
    {
        NSMutableDictionary *infoDict = [NSMutableDictionary dictionaryWithContentsOfFile:plistPath];
        [infoDict setObject:[NSNumber numberWithBool:hidden] forKey:@"LSUIElement"];
        [infoDict writeToFile:plistPath atomically:NO];
        [manager changeFileAttributes:[NSDictionary dictionaryWithObject:[NSDate date] forKey:NSFileModificationDate] atPath: [[NSBundle mainBundle] bundlePath]];
    }
}

Update:
Nate Flink pointed out that some of the NSFileManager methods used above are deprecated. He posted an answer with the replacement methods below: https://stackoverflow.com/a/12428472/100848

Answer 2

Updated version of the original awesome example by weichsel (thank you!). Xcode threw a couple warnings one of which is a deprecated method on NSFileManager. Updated here with non-deprecated methods from iOS 5.1

    NSString *plistPath = nil;
NSFileManager *manager = [NSFileManager defaultManager];
if ((plistPath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:@"mySpecial/PathTo.plist"])) 
{
    if ([manager isWritableFileAtPath:plistPath]) 
    {
        NSMutableDictionary *infoDict = [NSMutableDictionary dictionaryWithContentsOfFile:plistPath];
        [infoDict setObject:@"foo object" forKey:@"fookey"];
        [infoDict writeToFile:plistPath atomically:NO];
        [manager setAttributes:[NSDictionary dictionaryWithObject:[NSDate date] forKey:NSFileModificationDate] ofItemAtPath:[[NSBundle mainBundle] bundlePath] error:nil];
    }
}