iOS 下载功能：断点下载（暂停和开始）（NSURLConnectionDataDelegate方法）
1，model文件代码
文件名称：HMFileDownloader.h
#import <Foundation/Foundation.h>
@interface HMFileDownloader : NSObject
/**
* 所需要下载文件的远程URL(连接服务器的路径)
*/
@property (nonatomic, copy) NSString *url;
/**
* 文件的存储路径(文件下载到什么地方)
*/
@property (nonatomic, copy) NSString *destPath;
/**
* 是否正在下载(有没有在下载, 只有下载器内部才知道)
*/
@property (nonatomic, readonly, getter = isDownloading) BOOL downloading;
/**
* 用来监听下载进度
*/
@property (nonatomic, copy) void (^progressHandler)(double progress);
/**
* 用来监听下载完毕
*/
@property (nonatomic, copy) void (^completionHandler)();
/**
* 用来监听下载失败
*/
@property (nonatomic, copy) void (^failureHandler)(NSError *error);
/**
* 开始(恢复)下载
*/
- (void)start;
/**
* 暂停下载
*/
- (void)pause;
@end
文件名称：HMFileDownloader.m
#import "HMFileDownloader.h"
@interface HMFileDownloader() <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;
/**
* 完整文件的总长度
*/
@property (nonatomic, assign) long long totalLength;
@end
@implementation HMFileDownloader
/**
* 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-", self.currentLength];
[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
{
#warning 一定要判断
if (self.totalLength) return;
// 1.创建一个空的文件到沙盒中
NSFileManager *mgr = [NSFileManager defaultManager];
// 刚创建完毕的大小是0字节
[mgr createFileAtPath:self.destPath contents:nil attributes:nil];
// 2.创建写数据的文件句柄
self.writeHandle = [NSFileHandle fileHandleForWritingAtPath:self.destPath];
// 3.获得完整文件的长度
self.totalLength = response.expectedContentLength;
}
/**
* 2. 当接受到服务器的数据就会调用(可能会被调用多次, 每次调用只会传递部分数据)
*/
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// 累加长度
self.currentLength += data.length;
NSLog(@"=%lld==",self.currentLength);
// 显示进度
double progress = (double)self.currentLength / self.totalLength;
if (self.progressHandler) { // 传递进度值给block
self.progressHandler(progress);
}
// 移动到文件的尾部
[self.writeHandle seekToEndOfFile];
// 从当前移动的位置(文件尾部)开始写入数据
[self.writeHandle writeData:data];
}
/**
* 3. 当服务器的数据接受完毕后就会调用
*/
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// 清空属性值
self.currentLength = 0;
self.totalLength = 0;
if (self.currentLength == self.totalLength) {
// 关闭连接(不再输入数据到文件中)
[self.writeHandle closeFile];
self.writeHandle = nil;
}
if (self.completionHandler) {
self.completionHandler();
}
}
/**
* 请求错误(失败)的时候调用(请求超时\断网\没有网, 一般指客户端错误)
*/
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
if (self.failureHandler) {
self.failureHandler(error);
}
}
@end
2、将上述两个文件拖到工程中
3、在控制器文件中导入
#import "HMFileDownloader.h"
声明
@property (nonatomic, strong)NSString *url;
@property (retain, nonatomic) UIProgressView *progressView;
@property (nonatomic, strong) HMFileDownloader *fileDownloader;
- (void)viewDidLoad
{
_progressView=[[UIProgressView alloc]init];
_progressView.frame=CGRectMake(10, 150, 170, 20);
[self.view addSubview:_progressView];
[self fileDownloader];
}
- (void)fileDownloader
{
if (!_ViewCont.fileDownloader) {
_fileDownloader = [[HMFileDownloader alloc] init];
// 需要下载的文件远程URL
_fileDownloader.url = @"http://192.168.1.9:8080/wyhouAppServices/upload/app_user/iOS%207%20Cookbook.pdf";
// 文件保存到什么地方1
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSString *filepath = [caches stringByAppendingPathComponent:@"20Cookbook.pdf"];
// 文件保存到什么地方2
NSURL *targetURL = [NSURL URLWithString:_ViewCont.fileDownloader.url];
NSString *docPath = [self documentsDirectoryPath];
// Combine the filename and the path to the documents dir into the full path
NSString *pathToDownloadTo = [NSString stringWithFormat:@"%@/%@", docPath, [targetURL lastPathComponent]];
_fileDownloader.destPath = pathToDownloadTo;
// typeof(10) a = 20; // int a = 20;
__weak typeof(self) vc = self;
_fileDownloader.progressHandler = ^(double progress) {
vc.progressView.progress=progress;
// _progressView.progress = progress;
};
_fileDownloader.completionHandler = ^{
NSLog(@"------下载完毕");
};
_fileDownloader.failureHandler = ^(NSError *error){
};
}else{
_progressView.progress= _ViewCont.progressView.progress;
__weak typeof(self) vc = self;
_fileDownloader.progressHandler = ^(double progress) {
vc.progressView.progress=progress;
//
};
NSLog(@"------");
}
// return _fileDownloader;
}
-(void)dealloc{
_progressView.progress=_progressView.progress;
}
// 按钮文字: "开始", "暂停"
- (void)start { // self.currentLength == 200
if (_fileDownloader.isDownloading) { // 暂停下载
[_fileDownloader pause];
[_testBtn setTitle:@"恢复" forState:UIControlStateNormal];
} else { // 开始下载
[_fileDownloader start];
[_testBtn setTitle:@"暂停" forState:UIControlStateNormal];
}
}
