NSString Category for create revsered string and lexically sorted string.

NSString+SPUtils.m

/*
	NSString+SPUtils

	Category for NSString

	-reversedString 
	: create reversed string.
		NSString *reversed = [@"AbcdE" reversedString]; // reversed = @"EdcbA"

	: create lexically sorted string.
		NSString *sorted = [@"ae3ceox" sortedString]; // sorted = @"3aceeox"

	23. 04. 13.
	by sooop.

*/
#import <Foundation/Foundation.h>

@interface NSString (SPUtils)
-(NSString*)reversedString;
-(NSString*)sortedString;
@end;

@implementation NSString (SPUtils)
-(NSString*)reversedString
{
	NSUInteger length = [self length], idx;
	char *cString = (char*)malloc(sizeof(char)*(length+1));
	strcpy(cString,[self UTF8String]);
	char temp;
	for(idx=0;idx<length/2;idx++) {
		temp = *(cString + idx);
		*(cString + idx) = *(cString + length - 1 - idx);
		*(cString + length - 1 - idx) = temp;
	}
	NSString *reversedString = [NSString stringWithUTF8String:cString];
	free(cString);
	return reversedString;
}

-(NSString*)sortedString
{
	NSString *resultString;
	@autoreleasepool {
		NSMutableArray *characters = [NSMutableArray array];
		NSArray *sortedArray;
		NSUInteger idx;
		for(idx=0;idx<[self length];idx++) {
			[characters addObject:[self substringWithRange:NSMakeRange(idx,1)]];
		}
		NSSortDescriptor *strDiscriptor = [[NSSortDescriptor alloc] initWithKey:@"description" ascending:YES];
		NSArray *discs = @[strDiscriptor];
		sortedArray = [characters sortedArrayUsingDescriptors:discs];
		NSMutableString *string = [NSMutableString string];
		for(idx=0;idx<[self length];idx++) {
			[string appendString:[sortedArray objectAtIndex:idx]];
		}
		resultString = [string copy];
	}
#if __has_feature(objc_arc)
	return resultString;
#else
	return [resultString autorelease];
#endif
}
@end