iOS get day difference by NSDateComponents

+ (NSInteger) daysdifference:(NSString*)start end:(NSString*)end
{
    //start = @"2013-01-26";
    //end = @"2013-02-09";
    NSDateFormatter *df = [[NSDateFormatter alloc]init];
    [df setDateFormat:@"yyyy/MM/dd"];
    NSDate *startDate = [df dateFromString:start];
    NSDate *endDate = [df dateFromString:end];
    
    NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *components = [gregorianCalendar components:NSDayCalendarUnit
                                                        fromDate:startDate
                                                          toDate:endDate
                                                         options:0];
    return components.day;
}

iOS NSDateFormatter

First of all, you can use [NSDate date] to get current date, then NSDateFormatter to set the format you want. That's all.

    NSDate *srcdate = [NSDate date];
    NSDateFormatter *date = [[NSDateFormatter alloc] init];
    date.dateFormat = @"yyyy/MM/dd";
    
    NSString *datefrom = [NSString stringWithFormat:@"%@", [date stringFromDate:srcdate]];

yyyy
yy
MM(numeric)
MMM(Jan, Feb...)
MMMM(full Month)
dd
K(12)
H(24)
mm
ss
aa(AM/PM)
EEE(Week)
EEEE(Week Full)

iOS jump to dedicated tab page

self.tabBarController.selectedIndex = 1;