#import <WSDatePicker/WSDatePicer.h>

    /// instance
    WSDatePickerController *b = [WSDatePickerController new];
    /// set type as you like
    b.pickerType = WSDatePickerTypeYEARANDMONTHANDDAY;

    /// set default date
    NSDateFormatter *format = [NSDateFormatter new];
    [format setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *dt = [format dateFromString:@"2016-12-12 12:12:12"];
    b.defaultDate = dt;

    ///callback block
    [b setCallback:^(NSInteger year, NSInteger month, NSInteger day, NSInteger hour, NSInteger minute, NSInteger second) {
        NSLog(@"%d  %d  %d  %d  %d  %d",year,month,day,hour,minute,second);
    }];
    /// ok,last, present
    [self presentViewController:b animated:YES completion:nil customerAnimated:YES];