iOS开发中文件的上传和下载功能的基本实现

@interface YYFileSingleDownloader : YYFileDownloader
/**
 *  开始的位置
 */
@property (nonatomic, assign) long long begin;
/**
 *  结束的位置
 */
@property (nonatomic, assign) long long end; 
@end

YYFileSingDownloader.m文件
复制代码
#import "YYFileSingleDownloader.h"
@interface YYFileSingleDownloader() <NSURLConnectionDataDelegate>
/**
 * 连接对象
 */
@property (nonatomic, strong) NSURLConnection *conn;

 

/**
 *  写数据的文件句柄
 */
@property (nonatomic, strong) NSFileHandle *writeHandle;
/**
 *  当前已下载数据的长度
 */
@property (nonatomic, assign) long long currentLength;
@end

复制代码
@implementation YYFileSingleDownloader

 

- (NSFileHandle *)writeHandle
{
    if (!_writeHandle) {
        _writeHandle = [NSFileHandle fileHandleForWritingAtPath:self.destPath];
    }
    return _writeHandle;
}

/**
 * 开始(恢复)下载
 */
- (void)start
{
    NSURL *url = [NSURL URLWithString:self.url];
    // 默认就是GET请求
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    // 设置请求头信息
    NSString *value = [NSString stringWithFormat:@"bytes=%lld-%lld", self.begin + self.currentLength, self.end];
    [request setValue:value forHTTPHeaderField:@"Range"];
    self.conn = [NSURLConnection connectionWithRequest:request delegate:self];
    
    _downloading = YES;
}

/**
 * 暂停下载
 */
- (void)pause
{
    [self.conn cancel];
    self.conn = nil;
    
    _downloading = NO;
}

#pragma mark - NSURLConnectionDataDelegate 代理方法
/**
 *  1. 当接受到服务器的响应(连通了服务器)就会调用
 */
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response