One, midnight Countdown "Getting Started with Apple iOS instance programming tutorial"

Source: Internet
Author: User

The app is used to calculate the remaining time from 12:00 midnight.

Current version of SDK 8.4 Xcode

Run Xcode Select Create a new Xcode project->single View application named minutestomidnight

(1) Open ViewController.h file in Xcode

(Red is the added code)

#import <UIKit/UIKit.h>

@interface viewcontroller: uiviewcontroller

{

nstimer *timer;

iboutlet UILabel *countdownlabel;

}

@property (nonatomic,retain)nstimer *timer;

@property (nonatomic,retain)iboutlet UILabel *countdownlabel;

-(void) OnTimer;

@end

(2) Open viewcontroller.m file in Xcode

#import "ViewController.h"

@interface viewcontroller ()

@end

@implementation Viewcontroller

@synthesize timer;

@synthesize Countdownlabel;

-(void) viewdidload {

[Super viewdidload];

additional setup after loading the view, typically from a nib.

[countdownlabel setFont: [uifont fontwithname:@ "Dblcdtempblack" Size :]];//font size

    Countdownlabel text = @ "00:00:00" ; Initialize the value of the label

self. Timer = [nstimer scheduledtimerwithtimeinterval:1.0 target: Self selector:@selector(onTimer) userInfo:nil repeats:YES ];

/*

Scheduledtimerwithtimeinterval: (nstimeinterval) seconds

Book a timer and set a time interval. Represents a value that enters a time interval object, in seconds, of a >0 floating-point type, and if the value is <0, the system defaults to 0.1

Target: (ID) atarget

Represents the Sent object, such as self

Selector: (SEL) Aselector

Method selector, which, within the time interval, chooses to invoke an instance method

UserInfo: (ID) userInfo

This parameter can be nil, and the timer is retained and freed by the object you specify when the timer fails.

Repeats: (BOOL) Yesorno

When yes, the timer loops continuously until it expires or is released, and when no, the timer is sent out once and then fails.

*/

}

-(void) didreceivememorywarning {

[Super didreceivememorywarning];

//Dispose of any resources, can be recreated.

}

-(void) OnTimer

{

nsdate *now = [nsdate date];

Nscalendar *gregorian = [[nscalendar alloc]initwithcalendaridentifier: Nscalendaridentifiergregorian];

   /* nsdate--Represents an absolute point in time
       nstimezone--time zone information
  & nbsp    nslocale--Localization information
       nsdatecomponents--a class that encapsulates a specific date, time, week, quarter, and so on
       nscalendar--Calendar class, which provides most of the date compute interfaces and allows you to convert between NSDate and nsdatecomponents
        NSDateFormatter--Used to convert between dates and strings

Nscalendar Calendar class ****//

The following methods are available for creating or initializing

+ (ID) Currentcalendar;

Get the current user's logical calendar (logical calendars)

+ (ID) Autoupdatingcurrentcalendar;

Get the current user's logical calendar (logical calendar), ...

-(ID) Initwithcalendaridentifier: (NSString *) identifier;

Initialize to various calendars. The range of identifier can be:

Nscalendaridentifiergregorian Solar Calendar

nscalendaridentifierbuddhist Buddhist Calendar

Nscalendaridentifierchinese China calendar

nscalendaridentifierhebrew Hebrew calendar

nscalendaridentifierislamic Islamic Calendar

nscalendaridentifierislamiccivil Islamic Civil calendar

Nscalendaridentifierjapanese Japan Calendar

*/

nsdatecomponents *datecomponents = [Gregorian components:(kcfcalendarunithour| Kcfcalendarunitminute| Kcfcalendarunitsecond) fromdate: now];

Nsinteger hour = [datecomponents hour];

nsinteger min = [datecomponents minute];

Nsinteger sec = [datecomponents second];

SEC = -sec;

min = -min;

hour = hour;

Countdownlabel. Text = [nsstring stringwithformat:@ "%ld:%ld:%ld", hour,min,sec];

}

@end

(3) UIView interface settings
-Black background

Click Main.storyboard

Select View Controller->view

Set the background to black

Select Attributes Inspector->background->black Color

(4) Add UILabel display countdown time

-Red Font

Select: Tools--Library; Drag a Label from the Library display menu to Main View

Color and font size of fonts from label Attributes

(5) write to the UILabel class file

Right-click the Label control and move the mouse over the circle behind "New referencing Outlet"; The circle becomes (+); Drag to a straight line to connect to the "view Controller";
Release the mouse Select button appears "Countdownlabel"; Pick it up.

Select: File--Save


Finally, in XCode, choose Build and then Running

(6) Simulator

This article originates from the online a blog tutorial, after I revise and test. Original Blog Address http://blog.sina.com.cn/s/blog_5fae23350100djg2.html

One, midnight Countdown "Getting Started with Apple iOS instance programming tutorial"

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.