xcode IOS开发之——下载-显示下载进度(03)

一 概述

在didReceiveResponse方法中，通过response.expectedContentLength获得下载文件的总大小在didReceiveData中将data中的数据添加到NSMutableData中，获取当前文件到大小当前文件/总文件赋值给progress显示

二 获取文件总大小和当前文件大小

2.1 获取当前文件大小

方法一

NSHTTPURLResponse *resp=(NSHTTPURLResponse *)response;

//NSLog(@"%@",resp.allHeaderFields);

long long fileLength=[resp.allHeaderFields[@"Content-Length"] longLongValue];

方法二

self.totalLength=response.expectedContentLength;

2.2 当前文件大小

声明并赋值NSMutableData

@property(nonatomic,strong) NSMutableData *fileData;

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{

NSLog(@"didReceiveResponse--");

self.fileData=[NSMutableData data];

}

将data数据添加到NSMutableData中

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

[self.fileData appendData:data];

}

2.3 计算进度

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

self.circleView.progress=(double)self.fileData.length/self.totalLength;

}

三 示例

3.1 代码

#import "ViewController.h"

#import "DACircularProgressView.h"

@interface ViewController ()

@property(nonatomic,strong) NSMutableData *fileData;

@property(nonatomic,assign) long long totalLength; //文件的长度

@property (weak, nonatomic) IBOutlet UIProgressView *progressView;

@property(nonatomic,weak) DACircularProgressView *circleView;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

DACircularProgressView *circleView=[[DACircularProgressView alloc]init];

circleView.frame=CGRectMake(100, 100, 100, 100);

circleView.trackTintColor=[UIColor blueColor];

circleView.progressTintColor=[UIColor redColor];

circleView.progress=0.0;

[self.view addSubview:circleView];

self.circleView=circleView;

}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

{

[self download];

}

-(void)download

{

//1-URL

NSURL *url=[NSURL URLWithString:@"http://localhost:8080//MJServer/resources/videos.zip"];

//2-请求

NSURLRequest *request=[NSURLRequest requestWithURL:url];

//3-下载

[NSURLConnection connectionWithRequest:request delegate:self];

}

#pragma 代理方法

//-请求失败时调用(请求超时，网络异常)

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error

{

NSLog(@"didFailWithError--");

}

//-接收到服务器的响应聚会调用

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

{

NSLog(@"didReceiveResponse--");

self.fileData=[NSMutableData data];

//取出文件的总长度

NSHTTPURLResponse *resp=(NSHTTPURLResponse *)response;

//NSLog(@"%@",resp.allHeaderFields);

long long fileLength=[resp.allHeaderFields[@"Content-Length"] longLongValue];

//NSLog(@"%lld",fileLength);

//NSLog(@"%lld",response.expectedContentLength);

self.totalLength=response.expectedContentLength;

}

//当接收到服务器返回到实体数据时调用(具体内容，这个内容可被调用多次)

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{

//static int total=0;

//total+=data.length;

//NSLog(@"didReceiveData--%d---%d",data.length,total);

[self.fileData appendData:data];

//self.progressView.progress=(double)self.fileData.length/self.totalLength;

self.circleView.progress=(double)self.fileData.length/self.totalLength;

}

//加载完毕后调用(服务器的数据已经完全返回后)

-(void)connectionDidFinishLoading:(NSURLConnection *)connection

{

NSLog(@"connectionDidFinishLoading--");

//写入到沙盒中

NSString *cache= [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)lastObject];

NSString *file=[cache stringByAppendingPathComponent:@"videos.zip"];

[self.fileData writeToFile:file atomically:YES];

}

@end

3.2 效果图

四 存在的问题

由于将所有的数据添加到NSMutableData中，添加完成后，1次将数据写入到文件中，导致内存过大

参考链接