iPhone开发【十四】多线程开发之NSThread——子线程模拟耗时操作

[b][b]转载请注明出处，原文网址：/article/1354668.html
作者：张燕广[/b][/b]

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：



[cpp] view
plaincopy

#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：



[cpp] view
plaincopy

#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：

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