Python for Bioinformatics: Cocoa: sorting an array

Thursday, September 24, 2009

Cocoa: sorting an array

I went poking around in the header file "NSArray.h" and found some methods that were new to me.

• firstObjectCommonWithArray:
• removeObject:
• exchangeObjectAtIndex: withObjectAtIndex:
• sortedArrayUsingDescriptors:

// gcc -o arrays arraystuff.m -framework Foundation
// ./arrays
#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSUInteger i;
    NSMutableArray *mA1 = [NSMutableArray arrayWithCapacity:10];
    NSMutableArray *mA2 = [NSMutableArray arrayWithCapacity:10];
    for (i = 0; i < 6; i++) {
        [mA1 addObject:[NSNumber numberWithInt:i]];
    }
    for (i = 5; i < 10; i++) {
        [mA2 addObject:[NSNumber numberWithInt:i]];
    }
    NSNumber *x = [mA1 firstObjectCommonWithArray:mA2];
    NSLog(@"x %@", [x description]);
    
    [mA2 removeObject:[NSNumber numberWithInt:6]];
    NSLog(@"mA2 %@", [mA2 description]);
    
    [mA1 exchangeObjectAtIndex:0 withObjectAtIndex:2];
    NSLog(@"mA1 %@", [mA1 description]);
    
    NSSortDescriptor *sd;
    sd = [[[NSSortDescriptor alloc]
                initWithKey:@"intValue"
                ascending:NO] autorelease];
    NSArray *sdA = [NSArray arrayWithObject:sd];
    NSArray *a1 = [mA1 sortedArrayUsingDescriptors:sdA];
    NSLog(@"a1 %@", [a1 description]);
    
    [pool drain];
    return 0;
}

.. $ ./arrays
.. x 5
.. mA2 (
    5,
    7,
    8,
    9
)
.. mA1 (
    2,
    1,
    0,
    3,
    4,
    5
)
.. a1 (
    5,
    4,
    3,
    2,
    1,
    0
)