The code I use to display a date label in my weather app.

displayCurrentDate.m

- (void)displayCurrentDate
{
    // This grabs the current date and initializes it to 
    // the variable "now"
    NSDate *now = [[NSDate alloc] init];

    // This initializes the class that turns NSDate objects
    // into readable text strings
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    
    // Sets how the date will be represented (EEEE is a
    // code for full day name)
    [dateFormat setDateFormat:@"EEEE"];

    // Saves the full day name to the string "currentDayName"
    NSString* currentDayName = [[dateFormat stringFromDate:now] uppercaseString];
    
    // Sets how the date will be represented for the rest
    // of the date
    [dateFormat setDateFormat:@", MMMM dd, yyyy"];

    // Saves it to the string "currentDayDate"
    NSString* currentDayDate = [dateFormat stringFromDate:now];
    
    // This combines both strings above into one
    currentDay = [NSString stringWithFormat:@"%@%@", currentDayName, currentDayDate];
    
    // The following sets up and then applies the formatting
    // to the attributed string.

    // Sets the bold font (this could be called anything,
    // strongFont, bold, bolded, etc.)
    UIFont *boldFont = [UIFont fontWithName:@"Metric-Semibold" size:16.0];

    // Sets the regular font
    UIFont *regularFont = [UIFont fontWithName:@"Metric-Regular" size:17.0];

    // Sets the color for the text
    UIColor *textColor = [UIColor colorWithRed:(51/255.f) green:(51/255.f) blue:(51/255.f) alpha:1.0];
    
    // This sets tracking, I don't think it uses any of
    // the font's built-in formulas for kerning though.
    // From what I read I think it just adds a set amount
    // of space between each glyph.
    NSNumber *tracking = [NSNumber numberWithFloat:1.0];
    
    // This sets up the attributes to be applied to the
    // entire string.
    NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys:
                           regularFont, NSFontAttributeName,
                           textColor, NSForegroundColorAttributeName, nil];

    // These will be applied to a subset of the string
    // after the above is applied. As you can guess from
    // the variable names, this is how we'll set our 
    // bold font
    NSDictionary *subAttrs = [NSDictionary dictionaryWithObjectsAndKeys:
                              boldFont, NSFontAttributeName,
                              tracking, NSKernAttributeName, nil];

    // The way it works is you tell it to apply a specific
    // formatting style for a specific range of the string.
    // What we do here is make a range that goes from the 
    // start of the string (0) to the end of the day name
    // (currentDayName.length).
    const NSRange range = NSMakeRange(0, currentDayName.length);
    
    // Now we initialize our attributed string with its
    // contents set to the combined NSString currentDay
    NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:currentDay
                                                                                       attributes:attrs];

    // Then we apply the bolded style attributes 
    // (subAttrs) to the attributed string for the 
    // aforementioned range
    [attributedText setAttributes:subAttrs range:range];
    
    // Now we set our finalized attributed string as 
    // the text for the current day label.
    [currentDayField setAttributedText:attributedText];

    // And I like to set the background color on labels
    // explicitly because when I first started building 
    // this app it seemed like the code for displaying
    // labels was getting run multiple times, thereby
    // placing labels on top of each other. It doesn't
    // seem to do it anymore, but I'm still a bit leery.
    // I think this is what you call Cargo cult programming.
    [currentDayField setBackgroundColor:[UIColor whiteColor]];
}