iOS网络编程（四）
小文件下载：就以下载一个图片视频为例
1.//耗时操作[NSData dataWithContentsOfURL:url]
-(void)download1
{
//1.url
NSURL*url = [NSURLURLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"];
//2.下载二进制数据
NSData *data = [NSData dataWithContentsOfURL:url];
//3.转换
UIImage *image = [UIImage imageWithData:data];
}
2.采用发送请求获取图片，视频
//1.无法监听进度
//2.内存飙升
-(void)download2
{
//1.url
// NSURL *url = [NSURL URLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"];
NSURL*url = [NSURLURLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"];
//2.创建请求对象
NSURLRequest*request = [NSURLRequestrequestWithURL:url];
//3.发送请求
[NSURLConnectionsendAsynchronousRequest:requestqueue:[NSOperationQueuemainQueue]completionHandler:^(NSURLResponse*_Nullableresponse,NSData*_Nullabledata,NSError*_NullableconnectionError) {
//4.转换
//UIImage *image = [UIImage imageWithData:data];
//
//self.imageView.image = image;
//NSLog(@"%@",connectionError);
//4.写数据到沙盒中
NSString*fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask,YES)lastObject]stringByAppendingPathComponent:@"123.mp4"];
[datawriteToFile:fullPathatomically:YES];
}];
}
3. //内存飙升,这种方法可以监听进度
-(void)download3
{
//1.url
// NSURL *url = [NSURL URLWithString:@"http://imgsrc.baidu.com/forum/w%3D580/sign=54a8cc6f728b4710ce2ffdc4f3cec3b2/d143ad4bd11373f06c0b5bd1a40f4bfbfbed0443.jpg"];
NSURL*url = [NSURLURLWithString:@"http://120.25.226.186:32812/resources/videos/minion_01.mp4"];
//2.创建请求对象
NSURLRequest*request = [NSURLRequestrequestWithURL:url];
//3.发送请求
[[NSURLConnectionalloc]initWithRequest:requestdelegate:self];
}
#pragma mark NSURLConnectionDataDelegate
-(void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
{
NSLog(@"didReceiveResponse");
//得到文件的总大小(本次请求的文件数据的总大小)
self.totalSize= response.expectedContentLength;
}
-(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
{
// NSLog(@"%zd",data.length);
[self.fileData appendData:data];
//进度=已经下载/文件的总大小
NSLog(@"%f",1.0*self.fileData.length/self.totalSize);
}
-(void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error
{
}
-(void)connectionDidFinishLoading:(NSURLConnection*)connection
{
NSLog(@"connectionDidFinishLoading");
//4.写数据到沙盒中
NSString*fullPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask,YES)lastObject]stringByAppendingPathComponent:@"123.mp4"];
[self.fileDatawriteToFile:fullPathatomically:YES];
NSLog(@"%@",fullPath);
}
1、同步请求可以从因特网请求数据，一旦发送同步请求，程序将停止用户交互，直至服务器返回数据完成，才可以进行下一步操作，
2、异步请求不会阻塞主线程，而会建立一个新的线程来操作，用户发出异步请求后，依然可以对UI进行操作，程序可以继续运行
