【代码笔记】iOS-UILable电子表显示

一，效果图。

二，代码。

RootViewController.h

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController
{
    UILabel *label;
    NSDateFormatter  *dateFormatter ;
}
@end

RootViewController.m

#import "RootViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    //label
    label=[[UILabel alloc]initWithFrame:CGRectMake(50, 100, 200, 200)];
    label.backgroundColor=[UIColor redColor];
    [self.view addSubview:label];

    //定时器
    [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateTime) userInfo:nil repeats:YES];

    dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"HH:mm:ss"];

}
- (void)updateTime
{
    label.text = [dateFormatter stringFromDate:[NSDate date]];
}