数据未保存在NSUserDefaults中

Question

i having a problem with my NSUserdefaults. When i type in the name in the textbox and click on the highscore the application will not response anything and the keypad will still be on the screen. When i tried to load the data, it say that the data for name is nil. The score that i have is 90. Can someone please tell me what is wrong with my coding.

Lots of thanks.

-(IBAction)savehighscore_button {


    int i, ii = -1;

    struct high_score {
        NSString *name;
        int highScore;
    };

    struct high_score structArray[10];

    NSUserDefaults *userPreferences = [NSUserDefaults standardUserDefaults];

    for (i=0; i<10; i++) {

        if ([userPreferences stringForKey :[NSString stringWithFormat:@"highScoreNameEntry%d",i]]!=nil && [userPreferences stringForKey :[NSString stringWithFormat:@"highScoreEntry%d"]]!=nil) {
        structArray[i].name= [userPreferences stringForKey:[NSString stringWithFormat:@"highScoreNameEntry%d",i]];
            structArray[i].highScore = [userPreferences integerForKey:[NSString stringWithFormat:@"highScoreEntry%d",i]];
            ii = i;
        }
    }
    if (myScore >0) {
        for (i==ii; i>=0; i--) {
            if (myScore > structArray[i].highScore) {
                if (i<9) {
                    structArray[i+1] = structArray[i];
                    structArray[i].name = nametextbox.text;
                    structArray[i].highScore = myScore;

                    if (i==ii && i<9) {
                        structArray[i+1].name = nametextbox.text;
                        structArray[i+1].highScore = myScore;
                        ii=i+i;
                    }

                    else if(i==ii && i<9) {
                        structArray[i+1].name = nametextbox.text;
                        structArray[i+1].highScore = myScore;
                        ii=i+1;
                    }
                }
            }

            if (ii==-1 && myScore >0) {
                structArray[0].name = nametextbox.text;
                structArray[0].highScore = myScore;
                ii=0;
            }
            for (i=0; i<=ii; i++) {
                [userPreferences setObject:structArray[i].name forKey:[NSString stringWithFormat:@"highScoreNameEntry%d",i]];
                [userPreferences setInteger:structArray[i].highScore forKey:[NSString stringWithFormat:@"highScoreEntry%d",i]];
            }
        }
    }

}

Answer 1

Anything saved into user defaults must be of a standard PLIST-compliant class (NSArray, NSDictionary, NSNumber, NSString, NSDate, NSData, NSValue). If it's not one of those, it has to be archived as an NSData instance (and therefore be NSCoding compliant) or packed into an NSValue if it's compatible.

That said, you're making this far more difficult on yourself than you need to. Why not have an array (the high score descriptor container) of dictionaries (each is a descriptor for a high score) that hold a name (an NSString) and the score (an NSNumber)? Each dictionary describes a high score for a given name. You can then store the whole thing by using -setObject:yourArray forKey:@"HighScores" .

Since you only get immutable copies back from NSUserDefaults, you'll want to ask for a -mutableCopy of the high scores array (don't forget to release it) when you want to modify things. Either replace a score or delete/add.

Using this approach, you don't have to resort to the (sorry for this) ghastly "string#" approach with a fixed number of scores. Your array will only contain the existing high scores. No waste and all 100% standard Cocoa classes that are fully PLIST'able with no extra work. This also lets you easily sort the array using sort descriptors (sorted by the key you used to store the score number in the dictionary).

Some basic code:

/* Build a fake high scores array */

NSMutableArray * highScores = [NSMutableArray array];

// Bob's score
NSDictionary * bob = [NSDictionary dictionaryWithObjectsAndKeys:
        @"Bob", @"name", 
        [NSNumber numberWithInt:8234323], @"score", 
        nil];
[highScores addObject:bob];

// Jane's score
NSDictionary * jane = [NSDictionary dictionaryWithObjectsAndKeys:
        @"Jane", @"name", 
        [NSNumber numberWithInt:92346345], @"score", 
        nil];
[highScores addObject:jane];

// Donald's score
NSDictionary * donald = [NSDictionary dictionaryWithObjectsAndKeys:
        @"Donald", @"name", 
        [NSNumber numberWithInt:5272348], @"score", 
        nil];
[highScores addObject:donald];

// Sort by high score
NSSortDescriptor * sort = [[NSSortDescriptor alloc] initWithKey:@"score" 
                                                      ascending:NO];
[highScores sortUsingDescriptors:[NSArray arrayWithObject:sort]];
[sort release];

// Store in user defaults
[[NSUserDefaults standardUserDefaults] setObject:highScores 
                                          forKey:@"HighScores"];

Answer 2

不要忘记使用：

[userPreferences synchronize];