UIImage from a URL that change by date

my question is simple, i want to load a UIImage from an URL, but this URL change pro开发者_如何学JAVAgrammatically by date.

Example Today the url is http://www.abc.com/2011-10-13/alfa.jpg

tomorrow is http://www.abc.com/2011-10-14/alfa.jpg

the only thing that change is the date part, how can i figure my app load that "alfa.jpg" at current date everytime i start it?

Thanks!

You should use [NSDate date] which returns the current date and time according to the device time (assuming your device time doesn't differ from the actual by more than a day). Then you should format the date according to your url. Something like-

NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy-MM-dd"];
NSString* dateString = [formatter stringFromDate:[NSDate date]];
[formatter release];

Use an NSDateFormatter to generate the part of the string that varies with time.

NSDateFormatter * dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd"];

NSString * datePart = [dateFormatter stringFromDate:[NSDate date]];

NSString * theURLString = [NSString stringWithFormat:@"http://www.abc.com/%@/alfa.jpg", datePart];

You will have to maintain a mechanism to check whether if the image for the day has been downloaded to avoid downloading it again.

Create a template of the url you are using nstring and a DateFormatter object...

NSDateFormatter *df   = [[[NSDateFormatter alloc] init] autorelease];
[df setDateFormat:@"yyyy-MM-dd"];
NSString *todayStr    = [df stringFromDate:[NSDate date]];

NSString *todayUrl    = [NSString stringWithFormat:@"http://www.abc.com/%@/alfa.jpg", todayStr];

todayUrl has the url for today!

Its an easy task just format your URL string using current date like,

NSString *URLString = [[NSString alloc] initWithFormat:@"http://www.abc.com/%@/alfa.jpg", currentDate];

Then use this string for URL request.