iOS文件下載

jopen 11年前發布 | 55K 次閱讀 IOS iOS開發 移動開發

iOS</span>開發中會經常用到文件上傳下載的功能，這篇文件將介紹一下如何結合asp.net webservice實現文件上傳下載。 
首先，讓我們看下文件下載。

這里我們下載cnblogs上的一個zip文件。使用NSURLRequest+NSURLConnection可以很方便的實現這個功能。在 asp.net webservice中可以將文件的地址返回到iOS系統，iOS系統再通過這個url去請求下載該文件。這里為了簡單起見，直接將url寫道代碼里面了。我們可以使用兩種方式去下載文件。

1、同步下載文件：

    NSString *urlAsString = @"http://files.cnblogs.com/zhuqil/UIWebViewDemo.zip";   
            NSURL    *url = [NSURL URLWithString:urlAsString];   
            NSURLRequest *request = [NSURLRequest requestWithURL:url];   
            NSError *error = nil;   
            NSData   *data = http://www.cnblogs.com/zhwl/archive/2012/07/13/[NSURLConnection sendSynchronousRequest:request   
                                                   returningResponse:nil   
                                                               error:&error];   
            /* 下載的數據 */   
            if (data != nil){   
                NSLog(@"下載成功");   
                if ([data writeToFile:@"UIWebViewDemo.zip" atomically:YES]) {   
                    NSLog(@"保存成功.");   
                }   
                else   
                {   
                    NSLog(@"保存失敗.");   
                }   
            } else {   
                NSLog(@"%@", error);   
            }
2.異步下載
    DownLoadingViewController.h



//  DownLoadingViewController.h   
//  DownLoading   
//   
//  Created by skylin zhu on 11-7-30.   
//  Copyright 2011年 mysoft. All rights reserved.   
//   

#import   

@interface DownLoadingViewController : UIViewController {   
    NSURLConnection *connection;    
    NSMutableData *connectionData;   
}   
@property (nonatomic,retain) NSURLConnection *connection;     
@property (nonatomic,retain) NSMutableData *connectionData;   
@end   

DownLoadingViewController.m  

//  DownLoadingViewController.m   
//  DownLoading   
//   
//  Created by skylin zhu on 11-7-30.   
//  Copyright 2011年 mysoft. All rights reserved.   
//   

#import "DownLoadingViewController.h"   

@implementation DownLoadingViewController   
@synthesize connection,connectionData;   
- (void)dealloc   
{   
    [super dealloc];   
}   

- (void)didReceiveMemoryWarning   
{   
    // Releases the view if it doesn't have a superview.   
    [super didReceiveMemoryWarning];   

    // Release any cached data, images, etc that aren't in use.   
}   

#pragma mark - View lifecycle   


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.   
- (void)viewDidLoad   
{   
    [super viewDidLoad];   
    //文件地址   
    NSString *urlAsString = @"http://files.cnblogs.com/zhuqil/UIWebViewDemo.zip";   
    NSURL    *url = [NSURL URLWithString:urlAsString];   
    NSURLRequest *request = [NSURLRequest requestWithURL:url];   
    NSMutableData *data = http://www.cnblogs.com/zhwl/archive/2012/07/13/[[NSMutableData alloc] init];   
    self.connectionData = http://www.cnblogs.com/zhwl/archive/2012/07/13/data;   
    [data release];   
    NSURLConnection *newConnection = [[NSURLConnection alloc]   
                                      initWithRequest:request   
                                      delegate:self   
                                      startImmediately:YES];   
    self.connection = newConnection;   
    [newConnection release];   
    if (self.connection != nil){   
       NSLog(@"Successfully created the connection");   
    } else {   
        NSLog(@"Could not create the connection");   
    }   
}   




- (void) connection:(NSURLConnection *)connection   
            didFailWithError:(NSError *)error{   
    NSLog(@"An error happened");   
    NSLog(@"%@", error);   
}   
- (void) connection:(NSURLConnection *)connection   
              didReceiveData:(NSData *)data{   
    NSLog(@"Received data");   
    [self.connectionData appendData:data];   
}   
- (void) connectionDidFinishLoading   
:(NSURLConnection *)connection{   
    /* 下載的數據 */   

        NSLog(@"下載成功");   
        if ([self.connectionData writeToFile:@"UIWebViewDemo.zip" atomically:YES]) {   
            NSLog(@"保存成功.");   
        }   
        else   
        {   
            NSLog(@"保存失敗.");   
        }   

    /* do something with the data here */   
}   
- (void) connection:(NSURLConnection *)connection   
          didReceiveResponse:(NSURLResponse *)response{   
    [self.connectionData setLength:0];   
}   

- (void) viewDidUnload{   
    [super viewDidUnload];   
    [self.connection cancel];   
    self.connection = nil;   
    self.connectionData = http://www.cnblogs.com/zhwl/archive/2012/07/13/nil;   
}   

@end   </pre></span></span>
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