iOS 简单的分段下载文件

首先自己写个请求数据的类

首先.h文件

#import <Foundation/Foundation.h>

 @interface Downloaders : NSObject<NSURLConnectionDataDelegate>

@property (nonatomic, assign) long long beginpt;//下载的起始点

@property (nonatomic, assign) long long endpt;//下载的终点

@property(nonatomic,assign)long long currentLength;//下载的长度

@property(nonatomic,retain)NSString *url;

-(void)starts;

@end

 .m文件

#import "Downloaders.h"

#import <Foundation/Foundation.h>

@implementation Downloaders

{

}

-(id)init

{

    self = [super init];

    if(self)

    {

    }

    return self;

}

-(void)starts

{

    [self startDown];

}

-(void)startDown

{

    NSURL *urls =[NSURL URLWithString:self.url];

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:urls];

    NSString *value = [NSString stringWithFormat:@"bytes=%lld-%lld", self.beginpt + self.currentLength, self.endpt];

    [request setValue:value forHTTPHeaderField:@"Range"];

    [NSURLConnection connectionWithRequest:request delegate:self];

}

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

{

    NSString *path = [NSHomeDirectory()stringByAppendingString:@"/Documents"];

    NSString *fullpath = [path stringByAppendingPathComponent:@"tests.mp4"];

    NSFileManager *fiels= [NSFileManager defaultManager];

    if(![fiels fileExistsAtPath:fullpath])

    {

        [fiels createFileAtPath:fullpath contents:nil attributes:nil];

    }

    else

    {

      //  NSLog(@"fiel exsits......");

    }

    NSFileHandle *fielhandel = [NSFileHandle fileHandleForUpdatingAtPath:fullpath];

    [ fielhandel seekToFileOffset:self.beginpt + self.currentLength ];

    [fielhandel writeData:data];

    self.currentLength += data.length;

}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection

{

    self.currentLength = 0;

}

 然后在需要的地方调用

#import "ViewController.h"

#import "Downloaders.h"

@interface ViewController ()

{

    long long totallength;

}

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    [self getfielsize];

    long long sizes= 0;

    sizes  = totallength/4+1;

    for(int i=0;i<4;i++)

    {

        Downloaders *objc = [[Downloaders alloc]init];

        objc.url = @"http://172.16.1.92:97/meadia/test.mp4";

        objc.beginpt = i*sizes;

        objc.endpt = objc.beginpt+sizes-1;

        [objc starts];

    }

    // Do any additional setup after loading the view, typically from a nib.

}

-(void)getfielsize

{

    NSString *str = @"http://172.16.1.92:97/meadia/test.mp4";

    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:str]];

    request.HTTPMethod=@"HEAD";

    NSURLResponse *response = nil;

    [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];

    totallength = response.expectedContentLength;

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end