Dealing with military time (and some regular expression stuff too)

Had to convert military time into AM/PM. I thought there would be an easier way to do it, but couldn't find anything. Here's what I did:

First, I wrote a method to parse military time into an NSDateComponents object. Note that this uses a regular expression, which is a little tricky in iOS. Also, you could adjust the regex to parse AM/PM time into an NSDateComponents object.

- (NSDateComponents *) parseTimeStringIntoDateComponents: (NSString*) str {
 
	NSDateComponents *dc = nil;
	NSString *pattern = @"^([0-9]{2}):([0-9]{2})$";
	NSRegularExpression *regex;
	NSRange strRange = NSMakeRange(0, [str length]);
	NSError *error = NULL;
 
	regex = [NSRegularExpression regularExpressionWithPattern:pattern										  options:NSRegularExpressionCaseInsensitive 
				error:&error];
 
	if (error) {
		LogError(@"Error parsing time into date components - %@", [error description]);
	}
 
	int numberOfMatches = [regex numberOfMatchesInString:str options:NSRegularExpressionCaseInsensitive range:strRange];
	//NSLog(@"str: %@   matches:%d", str, numberOfMatches);
 
	if (numberOfMatches > 0) {
 
		NSTextCheckingResult *match = [regex firstMatchInString:str options:NSRegularExpressionCaseInsensitive range:strRange];
		int hrs = [[str substringWithRange:[match rangeAtIndex:1]] intValue];
		int min = [[str substringWithRange:[match rangeAtIndex:2]] intValue];
		//NSLog(@"TimeString: %@  -  hrs:%d, min:%d",str,hrs,min);
		dc = [[NSDateComponents alloc] init];
		[dc setHour:hrs];
		[dc setMinute:min];
 
	} else {
		LogError(@"Time string is not formatted properly and cannot be parsed into date components");
	}
	return dc;
}

I also had to display the time in AM/PM format, so I wrote this method take the NSDateComponent and parse it into a string:

-(NSString*)convertTimeFromMilitary: (NSDateComponents*)dc{
	// convert military time to AM/PM
	int mHr = dc.hour;
	int min = dc.minute;
 
	int hr;
	if(mHr == 0) {
		hr = 12;
	}else {
		hr = mHr % 12;
	}
 
	return [NSString stringWithFormat:@"%d:%.2d %@", hr, min, (mHr >= 12 ? @"PM" : @"AM")];
}