Sorting NSArray with blocks

iOS4 blocks introduced a new way to sort NSArray. There is no need to provide selectors or functions as comparators any more. All you need is to provide a comparator block which returns one of 3 NSComparator values and take to objects as an argument. The input and output is same as for the outdated selector/function way (you can hardly change general comparator interface) but now your comparator block captures you function context! Additionally all the code is in the same place.

Below is a bit of my recent work code that changes the order of sorting based on the class instance variable m_seatQuality value:

featuresArray = [[unsortedFeaturesArray sortedArrayUsingComparator: ^(id a, id b) {

DMSeatFeature *first = ( DMSeatFeature* ) a;

DMSeatFeature *second = ( DMSeatFeature* ) b;

if ( first.quality == second.quality )

return NSOrderedSame;

else

{

if ( eSeatQualityGreen == m_seatQuality

|| eSeatQualityYellowGreen == m_seatQuality

|| eSeatQualityDefault == m_seatQuality )

{

if ( first.quality < second.quality )

return NSOrderedAscending;

else

return NSOrderedDescending;

}

else // eSeatQualityRed || eSeatQualityYellow

{

if ( first.quality > second.quality )

return NSOrderedAscending;

else

return NSOrderedDescending;

}

}

}] retain];

Know your place

Jets app, designed to make you fly with ease. Our promo site is eventually released to the public. Next - AppStore submission. I hope to show you my dream app pretty soon :)

WARNING! Creating precompiled collator because collator is out of date. This is expensive!

Today I've found a nice iOS warning every second time I start up my application on the device: "WARNING! Creating precompiled collator because collator is out of date. This is expensive!". Apple's programmers are informative about the consequences but not that much about the causes. I don't get any other errors or warning.

Google also can hardly help to comprehend what's happening. There are only some anecdotal evidences that it happens on iOS 4.2.1 - same as my device is running. Some other sources suggest that the warning is due to framework bug and I will get rid of it tomorrow after iOS 4.3 installation (or iPhone SDK 4.3 setup).