[IOS]iphone之在视图上显示当前的时间，并且时间还在走。

iphone之在视图上显示当前的时间，并且时间还在走。

在RootViewController.h中：

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController {

NSTimer *_timer;

UILabel *timeLabel;

}

@property (nonatomic,retain) UILabel *timeLabel;

@end

在RootViewController.m中：

#import "RootViewController.h"

#import <stdarg.h>

@implementation RootViewController

@synthesize timeLabel;

-(id)init

{

self = [super init];

if (self) {

}

return self;

}

- (void)loadView {

UIView *back = [[UIView alloc] initWithFrame:[[UIScreen mainScreen]bounds]];

back.backgroundColor = [UIColor scrollViewTexturedBackgroundColor];

self.view = back;

[back release];

}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

- (void)viewDidLoad {

    [super viewDidLoad];

//

_timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(timerFunc) userInfo:nil repeats:YES];



//显示时间

timeLabel = [[UILabel alloc] initWithFrame:CGRectMake(20, 130, 200, 30)];

timeLabel.backgroundColor = [UIColor clearColor];

[self.view addSubview:timeLabel];

}



//每一秒都被调用一次

- (void)timerFunc

{

NSDateFormatter *formatter = [[[NSDateFormatter alloc] init]autorelease];

[formatter setDateFormat:@"MM/dd/YY HH:mm:ss"];

NSString *timestamp = [formatter stringFromDate:[NSDate date]];

[timeLabel setText:timestamp];//时间在变化的语句

NSLog(@"%@",timestamp);

}

此代码用了计数器的原理，

_timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(timerFunc) userInfo:nil repeats:YES];

每隔1秒调用一下timerFunc方法。

［好好学习，天天向上］