多线程开发之NSThread——子线程模拟耗时操作（★★★虽是转载，但是附上了个人理解，firecat推荐★★★）

文章来源：blog.csdn.net/m_changgong…

一、实现的功能：

a、演示多线程开发。

b、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 plain copy

#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 plain copy

#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：

************

二、firecat个人实践

a、添加了函数参数的传递。

b、子线程while循环，一边延时，主线程进度条一边走动。

// ViewController.m

// iphone1

// Created by firecat on 15-4-12.

#import "ViewController.h"

@interface ViewController () {

bool bStart;

}

- (IBAction)mybtnStart:(id)sender;

- (IBAction)mybtnEnd:(id)sender;

@property(weak, nonatomic) IBOutlet UILabel *mylabel;

@property(weak, nonatomic) IBOutlet UIProgressView *myprogress;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

- (IBAction)mybtnStart:(id)sender {

self.myprogress.progress = 0;

self.mylabel.text = @"0.00";

//开启一个新线程

[NSThread detachNewThreadSelector:@selector(doJobInBackground)

toTarget:self

withObject:nil];

bStart = YES;

}

//子线程，后台执行工作

- (void)doJobInBackground {

float f = 0.0;

NSNumber *var = [NSNumber numberWithFloat:f];

while (1) {

if (!bStart) {

return;

}

f += 0.1;

var = [NSNumber numberWithFloat:f];

//通知主线程执行更新操作

[self performSelectorOnMainThread:@selector(invalidateProgress:)

withObject:var //传递参数,必须是obj类型

waitUntilDone:NO];

//睡眠,模拟子线程中耗时操作

[NSThread sleepForTimeInterval:0.5];

if (f >= 1) {

return;

}

//更新进度

- (void)invalidateProgress:(NSNumber *)var {

self.myprogress.progress = var.floatValue;

self.mylabel.text = [NSString stringWithFormat:@"%.2f", var.floatValue];

}

- (IBAction)mybtnEnd:(id)sender {

bStart = NO;

}

@end