iOS 下载

 #import "ViewController.h"
 
 @interface ViewController ()
 @property (strong, nonatomic) NSMutableData *data;
 @end
 
 @implementation ViewController
 
 - (void)viewDidLoad
 {
     [super viewDidLoad];
     // Do any additional setup after loading the view, typically from a nib.
     NSString *url = @"";
     url = [url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
     NSURL *newUrl = [NSURL URLWithString:url];
 
     NSURLRequest*request=[[NSURLRequest alloc]initWithURL:newUrl cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:100.0];//设置缓存和超时
 
     NSURLConnection*connection=nil;
 
     connection=[[NSURLConnection alloc]initWithRequest:request delegate:self startImmediately:YES];
 }
 
 -(void)connection:(NSURLConnection*)connection didReceiveResponse:(NSURLResponse*)response
 
 {//该方法在响应connection时调用
 
     NSLog(@"response");
 
     self.data=[[NSMutableData alloc]init];
 
     NSHTTPURLResponse*httpResponse=(NSHTTPURLResponse*)response;
 
     if(httpResponse&&[httpResponse respondsToSelector:@selector(allHeaderFields)]){
 
         NSDictionary*httpResponseHeaderFields=[httpResponse allHeaderFields];
 
         //mFileSize=[[httpResponseHeaderFields objectForKey:@"Content-Length"]longLongValue];
 
     }//获取文件文件的大小
 
 }
 
 -(void)connection:(NSURLConnection*)connection didFailWithError:(NSError*)error
 
 {//出错时调用
 
     NSLog(@"error");
 }
 
 -(void)connection:(NSURLConnection*)connection didReceiveData:(NSData*)data
 
 {//接受数据，在接受完成之前，该方法重复调用
 
     NSLog(@"receive");
 
     [self.data appendData:data];
 //
 //    _displayLabel.text=[NSString stringWithFormat:(@"%6.1fkb/%6.1fkb"),[_datalength]/1024.0,mFileSize/1024.0];
 //
 //    [_progressViewsetProgress:[_datalength]/(float)mFileSize];
 
 }
 
 -(void)connectionDidFinishLoading:(NSURLConnection*)connection
 
 {//完成时调用
 
     NSLog(@"Finish");
 
     NSString*filePath=[[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES)objectAtIndex:]stringByAppendingPathComponent:@"android.mp3"];
 
     [_data writeToFile:filePath atomically:NO];//将数据写入Documents目录。
 
     NSLog(@"%@",filePath);
 
 }