关于NSURLSession的上传和下载
在IOS7.0后，苹果公司新推出了一个NSURLSession来代替NSURLConnection。NSURLConnection默认是在主线程执行的。而NSURLSession是在其他线程上执行的。本篇主要实现了下载和上传，比起NSURLConnection更加简单。线程控制掌握更加清晰。
#pragma mark - 下载
- (IBAction)DownLoad
{
//1.URL
NSString *urlStr = @"http://she.21cn.com/emotions/mingren/a/2014/0309/15/26645767.shtml";
NSURL *url = [NSURL URLWithString:urlStr];
//2.NSURLRequest
NSURLRequest *request = [NSURLRequestrequestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicytimeoutInterval:5.0];
//3.NSURLSession
NSURLSession *session = [NSURLSessionsharedSession];
NSURLSessionDownloadTask *downLoad = [session downloadTaskWithRequest:request completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
if (error) {
NSLog(@"error = %@",error.localizedDescription);
}else{
// location是下载的临时文件目录
NSLog(@"%@", location);
// 如果要保存文件,需要将文件保存至沙盒
// 1. 根据URL获取到下载的文件名
NSString *fileName = [urlStr lastPathComponent];
// 2. 生成沙盒的路径
NSArray *docs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [docs[0] stringByAppendingPathComponent:fileName];
NSURL *toURL = [NSURL fileURLWithPath:path];
// 3. 将文件从临时文件夹复制到沙盒,在iOS中所有的文件操作都是使用NSFileManager
[[NSFileManager defaultManager] copyItemAtURL:location toURL:toURL error:nil];
// 4. 将图像设置到UIImageView
dispatch_async(dispatch_get_main_queue(), ^{
UIImage *image = [[UIImage alloc] initWithContentsOfFile:path];
_imageView.image = image;
});
}
}];
//4.因为任务默认是挂起状态，需要恢复任务（执行任务）
[downLoad resume];
}
- (IBAction)upLoad
{
// 0. 判断imageView是否有内容
if (_imageView.image == nil) {
NSLog(@"image view is empty");
return;
}
// 0. 上传之前在界面上添加指示符
UIActivityIndicatorView *indicator = [[UIActivityIndicatorViewalloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
// 设置位置???
CGSize size = _imageView.bounds.size;
indicator.center = CGPointMake(size.width / 2.0, size.height / 2.0);
[self.imageView addSubview:indicator];
[indicator startAnimating];
// 1. URL
NSString *urlStr = @"http://192.168.3.251/uploads/123.jpg";
NSURL *url = [NSURL URLWithString:urlStr];
// 2. Request -> PUT,request的默认操作是GET
NSMutableURLRequest *request = [NSMutableURLRequestrequestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicytimeoutInterval:5.0f];
request.HTTPMethod = @"PUT";
// *** 设置网络请求的身份验证! ***
// 1> 授权字符串
NSString *authStr = @"admin:123456";
// 2> BASE64的编码,避免数据在网络上以明文传输
// iOS中,仅对NSData类型的数据提供了BASE64的编码支持
NSData *authData = [authStr dataUsingEncoding:NSUTF8StringEncoding];
NSString *encodeStr = [authData base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithCarriageReturn];
NSString *authValue = [NSString stringWithFormat:@"Basic %@", encodeStr];
[request setValue:authValue forHTTPHeaderField:@"Authorization"];
// 3. Session
NSURLSession *session = [NSURLSessionsharedSession];
// 4. UploadTask
NSData *imageData = UIImageJPEGRepresentation(_imageView.image, 0.75);
NSURLSessionUploadTask *upload = [session uploadTaskWithRequest:request fromData:imageData completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
// 上传完成后,data参数转换成string就是服务器返回的内容
NSString *str = [[NSStringalloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"OK -> %@", str);
if (error != nil) {
NSLog(@"ERROR -> %@", error.localizedDescription);
} else {
}
[NSThreadsleepForTimeInterval:5.0f];
dispatch_async(dispatch_get_main_queue(), ^{
[indicator stopAnimating];
[indicator removeFromSuperview];
});
}];
[upload resume];
}