Objective-C code for pulling daily predicted and actual electricity price data from ComEd.

Electricity Price Downloader

#import <Foundation/Foundation.h>

int main(int argc, char *argv[]) {
	@autoreleasepool {

	int day = 1;
	int month = 1;
	int year = 2007;	
	NSDateComponents *comps = [[NSDateComponents alloc] init];

			[comps setDay:day];
			[comps setMonth:month];
			[comps setYear:year];
	        
	        //build calendar
	NSCalendar *gregorian1 = [[NSCalendar alloc]
	                                 initWithCalendarIdentifier:NSGregorianCalendar];
	NSDate *startDate = [gregorian1 dateFromComponents:comps];
	
	//end date
	NSDate *todayDate = [NSDate date];

		    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
		    NSDateComponents *todayComponents = [gregorian components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:startDate];
		    NSInteger theDay = [todayComponents day];
		    NSInteger theMonth = [todayComponents month];
		    NSInteger theYear = [todayComponents year];

		    // now build a NSDate object for yourDate using these components
		    NSDateComponents *components = [[NSDateComponents alloc] init];
		    [components setDay:theDay]; 
		    [components setMonth:theMonth]; 
		    [components setYear:theYear];
		    NSDate *thisDate = [gregorian dateFromComponents:components];
		
		NSCalendar *calendar = [NSCalendar currentCalendar];

		NSDateComponents *differenceComponents = [calendar components:(NSDayCalendarUnit)
		                                                     fromDate:startDate
		                                                       toDate:todayDate
		                                                      options:0];
		
		NSMutableString *contentsMutableCopy = [[NSMutableString alloc] init];
		[contentsMutableCopy insertString: @"Date,Time,Predicted,Actual\n" atIndex:0];
		//NSLog(@"Days between dates: %ld", [differenceComponents day]);

		int n=0;
		for(n=0; n <= [differenceComponents day]; n++)  
		{
		    // now build a NSDate object for the next day
		    NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
		    [offsetComponents setDay:n];
		    NSDate *nextDate = [gregorian dateByAddingComponents:offsetComponents toDate:thisDate options:0];

			NSDateFormatter *DateFormatter = [[NSDateFormatter alloc] init];
			[DateFormatter setDateFormat:@"yyyyMMdd"];
			NSString *formattedDateString = [DateFormatter stringFromDate:nextDate];

            //today's prices string
            NSString *fullURL = [NSString stringWithFormat:@"http://rrtp.comed.com/rrtp/ServletFeed?type=pricingtabledual&date=%@", formattedDateString];
            
            //Get contents of fullURL
            NSURL *hourlyPriceURL = [NSURL URLWithString:fullURL];
            NSError *error = nil;
            NSString *contents = [[NSString alloc] initWithContentsOfURL:hourlyPriceURL encoding:NSUTF8StringEncoding error:&error];
            
            //strip out html from contents of URL contents
            contents = [contents stringByReplacingOccurrencesOfString:@"&cent;</td><td>" withString:@","];
            contents = [contents stringByReplacingOccurrencesOfString:@"&cent;</td></tr><tr>" withString:@"\n ,"];
            contents = [contents stringByReplacingOccurrencesOfString:@"<tr>" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@"<td>" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@"</tr>" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@"</td>" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@"<small>" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@"</small>" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@";" withString:@""];
            contents = [contents stringByReplacingOccurrencesOfString:@"M" withString:@"M,"];
            contents = [contents stringByReplacingOccurrencesOfString:@"&cent" withString:@""];


			NSString *combo = [formattedDateString stringByAppendingString:@","];  
			NSString *comboDatePrice = [combo stringByAppendingString:contents];

        //csv-ready string
        [contentsMutableCopy appendString: comboDatePrice];
		
		NSLog(@"comboDatePrice=%@",comboDatePrice);		
	}

   		NSError *error;           

		[contentsMutableCopy writeToFile:@"/Users/johnvoorhees/DropBox/electricityPrices.csv" atomically:NO encoding:NSUTF8StringEncoding error:&error];
	}
}