NSUSerDefaults with NSMutableArray sort by desc order - objective-c

Question

I'm breaking my head on why descending order sort is not working with the following code. I wanted to limit by top 5 scores and other logic. The scores would look like this: 22/30, 12/18, 34/38, 23/32 etc. I added/removed SortDescriptor to sort by descending order and it seems to work for the first 3 items but then is not sorting properly. Can somebody help?
- (NSMutableArray*) method1:(NSString *) mode byScore: (NSString *) score
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSMutableArray *array = [[defaults objectForKey:mode]mutableCopy];
if (!array)
{
array = [[NSMutableArray alloc] init];
}
NSLog(#"The content of array is%#", array);
if ([array count] < 5)
{
if (![array containsObject:score])
{
[array addObject:score];
// Need to sort here. But not too sure this is the right place
NSLog(#"The content of the sorted array upto 5 is%#", array);
}
}
else
{
if (![array containsObject:score])
{
if ([array lastObject] < score)
{
[array addObject:score];
// Need to sort here before I remove the last object
[array removeLastObject];
NSLog(#"The content of the sorted array else is%#",array);
}
}
}
[defaults setObject:array forKey:mode];
[defaults synchronize];
// I want the array in NSUserDefaults to be sorted in desc order
// don't know what to return here ==> the array object or the defaults object cast to NSMutableArray?
}

Answer 1

Helper function
static NSComparisonResult CompareFloats( float a, float b )
{
if ( a < b ) { return NSOrderedAscending ; }
else if ( a > b ) { return NSOrderedDescending ; }
return NSOrderedSame ;
}
Category on NSString
#implementation NSString (Stuff)
-(float)floatValueForFraction
{
NSArray * components = [ self componentsSeparatedByString:#"/" ] ;
return [ components[0] floatValue ] / [ components[1] floatValue ] ;
}
#end
Your method:
- (void)addScore:(NSString*)score forMode:(NSString*)mode
{
NSUserDefaults * defaults = [ NSUserDefaults standardUserDefaults ] ;
NSArray * scores = [ defaults objectForKey:mode ] ;
scores = scores ? [ scores arrayByAddingObject:score ] : #[ score ] ;
scores = [ scores sortedArrayUsingComparator:^(NSString * a, NSString * b){
return CompareFloats( [ a floatValueForFraction ], [ b floatValueForFraction ] ) ;
}]
if ( scores.count > 5 ) { scores = [ scores subarrayWithRange:(NSRange){ .length = 5 } ] ; }
[ default setObject:scores forKey:mode ] ;
}
If you want the updated high scores after calling this method, just use [ [ NSUserDefaults standardUserDefaults ] objectForKey:<mode> ]. It's better to have your methods just do one thing.

Answer 2

One approach to sorting array:
First define a block getNumeratorAndDenominatorFromScoreString as follows:
BOOL (^getNumeratorAndDenominatorFromScoreString)(NSString *, NSInteger *, NSInteger *) = ^(NSString *scoreString, NSInteger *numeratorOut, NSInteger *denominatorOut) {
BOOL res = NO;
NSArray *components = [scoreString componentsSeparatedByString:#"/"];
if (components &&
[components count] == 2) {
res = YES;
if (numeratorOut) {
NSNumber *numeratorNumber = [components objectAtIndex:0];
*numeratorOut = [numeratorNumber integerValue];
}
if (denominatorOut) {
NSNumber *denominatorNumber = [components objectAtIndex:1];
*denominatorOut = [denominatorNumber integerValue];
}
}
return res;
};
Then use this block together with -[NSArray sortedArrayUsingComparator] to sort array:
NSArray *sortedArray = [array sortedArrayUsingComparator: ^(id obj1, id obj2) {
NSComparisonResult res = NSOrderedSame;
NSString *score1 = (NSString *)obj1;
NSString *score2 = (NSString *)obj2;
NSInteger numerator1, denominator1, numerator2, denominator2;
BOOL res1, res2;
res1 = getNumeratorAndDenominatorFromScoreString(score1, &numerator1, &denominator1);
res2 = getNumeratorAndDenominatorFromScoreString(score2, &numerator2, &denominator2);
if (res1
&& res2) {
CGFloat value1 = ((CGFloat)numerator1)/((CGFloat)denominator1);
CGFloat value2 = ((CGFloat)numerator2)/((CGFloat)denominator2);
if (value1 > value2) {
res = NSOrderedDescending;
} else if (value1 < value2) {
res = NSOrderedAscending;
}
}
return res;
}];
This will order array from least to greatest. To order from greatest to least, just replace
if (value1 > value2) {
res = NSOrderedDescending;
} else if (value1 < value2) {
res = NSOrderedAscending;
}
with
if (value1 > value2) {
res = NSOrderedAscending;
} else if (value1 < value2) {
res = NSOrderedDescending;
}
A readable structure for this method would be, in [mostly not] pseudocode
- (void)addScoreToHighscores:(NSString *)score withMethod:(NSString *)mode
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSArray *currentHighscores = [defaults arrayForKey:mode];
if (!currentHighscores) currentHighscores = [NSArray array];
if (![currentHighscores containsObject:score]) {
currentHighscores = [currentHighscores arrayByAddingObject:score];
//sort currentHighscores: adapt the above code so that we have
BOOL (^getNumeratorAndDenominatorFromScoreString)(NSString *, NSInteger *, NSInteger *) = //as above
NSArray *newHighscores = [currentHighscores sortedArrayUsingComparator:^(id obj1, id obj2) {
//as above
}];
//truncate newHighscores
if ([newHighscores count] > 5) {
newHighscores = [newHighscores subarrayWithRange:NSMakeRange(0,5)];
}
[defaults setObject:newHighscores forKey:mode];
} else {
//since score is already in currentHighscores, we're done.
return;
}
}
If you need to screen out scores the strings for which are not equal but the evaluations of the fractions for which are equal (#"1/2" and #"5/10"), you'll need to be more clever.
Here is the full code sketched out above:
- (void)addScoreToHighscores:(NSString *)score withMethod:(NSString *)mode
{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSArray *currentHighscores = [defaults arrayForKey:mode];
if (!currentHighscores) currentHighscores = [NSArray array];
if (![currentHighscores containsObject:score]) {
currentHighscores = [currentHighscores arrayByAddingObject:score];
//sort currentHighscores: adapt the above code so that we have
BOOL (^getNumeratorAndDenominatorFromScoreString)(NSString *, NSInteger *, NSInteger *) = ^(NSString *scoreString, NSInteger *numeratorOut, NSInteger *denominatorOut) {
BOOL res = NO;
NSArray *components = [scoreString componentsSeparatedByString:#"/"];
if (components &&
[components count] == 2) {
res = YES;
if (numeratorOut) {
NSNumber *numeratorNumber = [components objectAtIndex:0];
*numeratorOut = [numeratorNumber integerValue];
}
if (denominatorOut) {
NSNumber *denominatorNumber = [components objectAtIndex:1];
*denominatorOut = [denominatorNumber integerValue];
}
}
return res;
};
NSArray *newHighscores = [currentHighscores sortedArrayUsingComparator:^(id obj1, id obj2) {
NSComparisonResult res = NSOrderedSame;
NSString *score1 = (NSString *)obj1;
NSString *score2 = (NSString *)obj2;
NSInteger numerator1, denominator1, numerator2, denominator2;
BOOL res1, res2;
res1 = getNumeratorAndDenominatorFromScoreString(score1, &numerator1, &denominator1);
res2 = getNumeratorAndDenominatorFromScoreString(score2, &numerator2, &denominator2);
if (res1
&& res2) {
CGFloat value1 = ((CGFloat)numerator1)/((CGFloat)denominator1);
CGFloat value2 = ((CGFloat)numerator2)/((CGFloat)denominator2);
if (value1 > value2) {
res = NSOrderedDescending;
} else if (value1 < value2) {
res = NSOrderedAscending;
}
}
return res;
}];
//truncate newHighscores
if ([newHighscores count] > 5) {
newHighscores = [newHighscores subarrayWithRange:NSMakeRange(0,5)];
}
[defaults setObject:newHighscores forKey:mode];
} else {
//since score is already in currentHighscores, we're done.
return;
}
}