关键词:多线程 NSOperation NSOperationQueue 等待框
效果图如下:
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1、新建视图控制器ViewController(不带xib),作为根视图控制器,通过ViewController的-(void)loadView方法构建UI。
2、新建继承自NSOperation且实现协议NSURLConnectionDelegate的类DownLoadImageTask,DownLoadImageTask.h如下:
#import <Foundation/Foundation.h> @protocol DownLoadImageDelegate; @interface DownLoadImageTask : NSOperation<NSURLConnectionDelegate>{ int operationId; long long totalLength; BOOL done; } @property int operationId; @property(nonatomic,assign) id<DownLoadImageDelegate>downloadImageDelegate; @property(nonatomic,retain) NSMutableData *buffer; @property(nonatomic,retain) NSURLRequest *request; @property(nonatomic,retain) NSURLConnection *connection; - (id)initWithURLString:(NSString *)url; @end @protocol DownLoadImageDelegate //图片下载完成的委托 -(void)imageDownLoadFinished:(UIImage *)img; //更新图片下载进度条的值 -(void)updateDownProgress:(double) value; @end
DownLoadImageTask.m如下:
@implementation DownLoadImageTask @synthesize operationId; @synthesize downloadImageDelegate; @synthesize buffer; @synthesize request; @synthesize connection; - (id)initWithURLString:(NSString *)url{ NSLog(@"url=%@",url); self = [super init]; if(self){ request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]]; buffer = [NSMutableData data]; } return self; } //主要处理方法 -(void)start{ //或者main NSLog(@"DownLoadImageTask-start"); if(![self isCancelled]){ //暂停一下 [NSThread sleepForTimeInterval:1]; //设置connection及其代理 connection = [[NSURLConnection alloc]initWithRequest:request delegate:self]; if(connection!=nil){ while(!done){ [[NSRunLoop currentRunLoop]runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } } } } -(void)httpConnectEndWithError{ //[self hiddenWaiting]; NSLog(@"httpConnectEndWithError"); } -(void)dealloc{ buffer = nil; connection = nil; request = nil; downloadImageDelegate = nil; } #pragma NSURLConnection delegate methods //不执行缓存 -(NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse{ return nil; } //连接发生错误 -(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{ [self performSelectorOnMainThread:@selector(httpConnectEndWithError) withObject:self waitUntilDone:NO]; [buffer setLength:0]; } //收到响应 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{ NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response; if(httpResponse && [httpResponse respondsToSelector:@selector(allHeaderFields)]){ NSDictionary *httpResponseHeaderFields = [httpResponse allHeaderFields]; totalLength = [[httpResponseHeaderFields objectForKey:@"Content-Length"] longLongValue]; NSLog(@"totalLength is %lld",totalLength); } } //接收数据 -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{ //NSLog(@"didReceiveData..."); [buffer appendData:data]; double progressValue = totalLength==0?0:((double)([buffer length])/(double)totalLength); //更新进度条值 [downloadImageDelegate updateDownProgress:progressValue]; } //下载完毕 -(void)connectionDidFinishLoading:(NSURLConnection *)connection{ done = YES; UIImage *img = [[UIImage alloc] initWithData:buffer]; [downloadImageDelegate imageDownLoadFinished:img]; } -(BOOL)isConcurrent { //返回yes表示支持异步调用,否则为支持同步调用 return YES; } - (BOOL)isExecuting{ return connection == nil; } - (BOOL)isFinished{ return connection == nil; } @end
DownLoadImageTask中定义了协议DownLoadImageDelegate,ViewController需要实现协议DownLoadImageDelegate;DownLoadImageTask下载工作完成后,会回调ViewController实现的DownLoadImageDelegate协议中的方法。
2、ViewController.h如下:
#import "DownLoadImageTask.h" @interface ViewController:UIViewController<DownLoadImageDelegate>{ } @property(strong,nonatomic)NSOperationQueue *queue; @property(strong,nonatomic)UIImageView *appImgView; @end
ViewController.m如下:
#import "ViewController.h" #import "DownLoadImageTask.h" @implementation ViewController @synthesize queue; @synthesize appImgView; -(void)loadView{ //初始化视图 [self initViews]; //显示等待框 [self showWaiting]; NSString *url = @"http://hiphotos.baidu.com/newwen666666/pic/item/01ec7750863e49600cf3e3cc.jpg"; int index = 1; DownLoadImageTask *task = [[DownLoadImageTask alloc]initWithURLString:url]; task.downloadImageDelegate = self; task.operationId = index++; queue = [[NSOperationQueue alloc]init]; [queue addOperation:task]; } //初始化视图组件 -(void)initViews{ CGRect frame = [UIScreen mainScreen].applicationFrame; UIView *appView = [[UIView alloc]initWithFrame:frame]; self.view = appView; [self.view setBackgroundColor:[UIColor colorWithWhite:1.0 alpha:1.0]]; frame = CGRectMake(0, 0, frame.size.width, frame.size.height); appImgView = [[UIImageView alloc]initWithFrame:frame]; [self.view addSubview:appImgView]; } //展示等待框 -(void)showWaiting{ CGRect frame = CGRectMake(0, -20, 320, 480); int x = frame.size.width; int progressWidth = 150; int progressHeight = 32; frame = CGRectMake((x-progressWidth)/2, 100, progressWidth, progressHeight); UIProgressView *progress = [[UIProgressView alloc]initWithProgressViewStyle:UIProgressViewStyleBar]; progress.frame = frame; progress.progress = 0.0; progress.backgroundColor = [UIColor whiteColor]; UILabel *showValue = [[UILabel alloc]init]; frame = showValue.frame; frame.origin.x = CGRectGetMaxX(progress.frame)+10; frame.origin.y = CGRectGetMinY(progress.frame); frame.size.width = 45; frame.size.height = 15; showValue.frame = frame; showValue.backgroundColor = [UIColor redColor]; showValue.text = @"0.0"; int progressIndWidth = 32; int progressIndHeight = 32; frame = CGRectMake((x-progressIndWidth)/2, 100+32, progressIndWidth, progressIndHeight); UIActivityIndicatorView *progressInd = [[UIActivityIndicatorView alloc]initWithFrame:frame]; [progressInd startAnimating]; progressInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge; frame = CGRectMake((x-70)/2, 100+32+32, 80, 20); UILabel *waitinglabel = [[UILabel alloc]initWithFrame:frame]; waitinglabel.text = @"正在下载应用程序图片..."; waitinglabel.textColor = [UIColor redColor]; waitinglabel.font = [UIFont systemFontOfSize:15]; waitinglabel.backgroundColor = [UIColor clearColor]; frame = CGRectMake(0, -20, 320, 480); UIView *theView = [[UIView alloc]initWithFrame:frame]; theView.backgroundColor = [UIColor blackColor]; theView.alpha = 0.7; [progress setTag:100]; [theView addSubview:progress]; [showValue setTag:101]; [theView addSubview:showValue]; [theView addSubview:progressInd]; [theView addSubview:waitinglabel]; [theView setTag:110]; [self.view addSubview:theView]; } //隐藏等待框 -(void)hiddenWaiting{ [[self.view viewWithTag:110]removeFromSuperview]; } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); } #pragma mark DownLoadImageDelegate methods //展示下载完毕的图片 -(void)imageDownLoadFinished:(UIImage *)img{ //退出等待框 [self hiddenWaiting]; [appImgView setImage:img]; } //更新进度条的值 -(void)updateDownProgress:(double) value{ UIProgressView *progresss = (UIProgressView *)[self.view viewWithTag:100]; UILabel *showValue = (UILabel*)[self.view viewWithTag:101]; progresss.progress = value; showValue.text = [NSString stringWithFormat:@"%.1f%",(double)(value*100)]; } @end