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］