iPhone开发【十四】多线程开发之NSThread——子线程模拟耗时操作

转载请注明出处，原文网址：http://blog.csdn.net/m_changgong/article/details/8213964  作者：张燕广

实现的功能：1）演示多线程开发。2）子线程中模拟耗时操作，然后通知主线程更新进度条。

关键词：多线程 NSThread 定时器

1、新建视图控制器ViewController.m（不带xib），作为根视图控制器，通过ViewController的-(void)loadView方法构建UI，ViewController.h如下：

 #import <UIKit/UIKit.h>

 @interface ViewController : UIViewController{
     CGFloat progressValue; //进度条的值
 }

 @property(strong,nonatomic)UIProgressView *progress;
 @property(strong,nonatomic)UILabel *showValue;
 @property(strong,nonatomic)UIButton *startThread;

 @end

ViewController.m如下：

 #import "ViewController.h"

 @implementation ViewController
 @synthesize progress;
 @synthesize showValue;
 @synthesize startThread;

 -(void)loadView{
     CGRect appFrame = [UIScreen mainScreen].applicationFrame;
     UIView *view = [[UIView alloc]initWithFrame:appFrame];
     self.view = view;

     //设置背景颜色
     UIColor *bgcolor = [UIColor grayColor];
     [self.view setBackgroundColor:bgcolor];

     [self initViews];
 }

 //初始化视图组件
 -(void)initViews{
     //初始化progress
     CGRect frame = CGRectMake(50, 50, 200, 30);
     progress = [[UIProgressView alloc]initWithFrame:frame];
     [self.view addSubview:progress];

     //初始化showValue
     showValue = [[UILabel alloc]init];
     frame = showValue.frame;
     frame.origin.x = CGRectGetMaxX(progress.frame)+10;
     frame.origin.y = CGRectGetMinY(progress.frame);
     frame.size.width = 35;
     frame.size.height = 15;
     showValue.frame = frame;
     showValue.backgroundColor = [UIColor redColor];
     showValue.text = @"0.0";
     [self.view addSubview:showValue];

     //初始化startThread
     startThread = [[UIButton alloc]init];
     frame = startThread.frame;
     frame.origin.x = 110;
     frame.origin.y = 80;
     frame.size.width = 100;
     frame.size.height = 50;
     startThread.frame = frame;
     UIImage *img = [UIImage imageNamed:@"btn.png"];
     [startThread setBackgroundImage:img forState:UIControlStateNormal];
     [startThread setTitleColor:[UIColor colorWithRed:1.0 green:0 blue:0 alpha:1.0] forState:UIControlStateNormal];
     [startThread setTitle:@"开启子线程" forState:UIControlStateNormal];
     //设置事件
     [startThread addTarget:self action:@selector(startThreadButtonPressed) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:startThread];
 }

 //开启子线程
 -(void)startThreadButtonPressed{
     progress.progress = 0.0;
     showValue.text = @"0.0";
     startThread.hidden = YES;
     //该语句会让主线程堵塞2秒，这就是为什么要将耗时操作放在子线程的原因之一
     //[NSThread sleepForTimeInterval:2];

     //开启一个新线程
     [NSThread detachNewThreadSelector:@selector(doJobInBackground) toTarget:self withObject:nil];
 }

 //子线程，后台执行工作
 -(void)doJobInBackground{
     //睡眠,模拟子线程中耗时操作
     [NSThread sleepForTimeInterval:2];
     //通知主线程执行更新操作
     [self performSelectorOnMainThread:@selector(invalidateProgress) withObject:nil waitUntilDone:NO];
 }

 //更新进度
 -(void)invalidateProgress{
     progressValue = [progress progress];
     showValue.text = [NSString stringWithFormat:@"%.2f",progressValue];
     if(progressValue < 1.0){
         progress.progress = progressValue+0.02;
         //启动定时器
         [NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector(invalidateProgress) userInfo:nil repeats:NO];
     }else{
         progress.progress = 1.0;
         showValue.text = @"1.0";
         startThread.hidden = NO;
     }
 }

 - (void)viewDidUnload
 {
     [super viewDidUnload];
     // Release any retained subviews of the main view.
     progress = nil;
     showValue = nil;
     startThread = nil;
 }

 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
 {
     return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
 }

 @end

2、运行效果如下：