一个有趣的多线程应用实例

这个实例主要实现了隔相同的时间一张张加载图片在用for循环创建6个不同的图片视图上，且点击屏幕可使未完成的进程被取消，并退出即未加载的图片停止加载，有兴趣的朋友可以一试。（相应的注意点都已经在代码中注释）

#import "ViewController.h"

#define kUrl @"http://store.storeimages.cdn-apple.com/8748/as-images.apple.com/is/image/AppleInc/aos/published/images/s/38/s38ga/rdgd/s38ga-rdgd-sel-201601?wid=848&hei=848&fmt=jpeg&qlt=80&op_sharpen=0&resMode=bicub&op_usm=0.5,0.5,0,0&iccEmbed=0&layer=comp&.v=1454777389943"

@interface
ViewController (){

int tagValue;

UIImage *image;

NSMutableArray *threadArray;

}

@end

@implementation ViewController

-(void)viewDidLoad{

[super
viewDidLoad];

self.view.backgroundColor = [UIColor
whiteColor];

tagValue = 100;

threadArray = [NSMutableArray
array];

self.edgesForExtendedLayout =
0;

self.title =
@"多张图片";

[self.navigationController.navigationBar
setTitleTextAttributes:@{NSFontAttributeName:[UIFont
boldSystemFontOfSize:24],NSForegroundColorAttributeName:[UIColor
greenColor]}];

// 创建多个UIimageview

for (int row =
0; row<3; row++) {

for (int list =
0; list<2; list++) {

UIImageView *imageView = [[UIImageView
alloc]initWithFrame:CGRectMake(10+list*200,
10+row*200,
200, 200)];

imageView.tag =
tagValue++;

imageView.backgroundColor = [UIColor
redColor];

imageView.userInteractionEnabled =
YES;

[self.view
addSubview:imageView];

}

}

// 创建多个子线程

for (int index =
0; index<6; index++) {

[NSThread
detachNewThreadSelector:@selector(thread:)
toTarget:self
withObject:@(index)];

}

}

// 通过url加载网络图片

- (void)thread:(NSNumber *)index{

[threadArray
addObject:[NSThread
currentThread]];

NSThread *thread = [NSThread
currentThread];

[NSThread
sleepForTimeInterval:[index intValue]];//通过线程休眠实现顺序加载

if (thread.isCancelled ==
YES) {

[NSThread
exit];

}

NSData *data = [NSData
dataWithContentsOfURL:[NSURL
URLWithString:kUrl]];

image = [UIImage
imageWithData:data];

// ❤️❤️回到主线程

[self
performSelectorOnMainThread:@selector(updateUI:)
withObject:index waitUntilDone:YES];

}

// 更新UI

- (void)updateUI:(NSNumber *)index{

UIImageView *imageV = [self.view
viewWithTag:[index
integerValue]+100];

imageV.image =
image;

}

//点击屏幕取消未完成的线程

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{

NSLog(@"%@",threadArray);

for (int index =
0; index<6; index++) {

NSThread *thread =
threadArray[index];

if (thread.isFinished ==
NO) {

[thread cancel];//取消不是退出

}

}

}

@end