- (void)viewDidLoad {
[super viewDidLoad];
NSLog(@"%@",NSHomeDirectory());
//取得已下載數據大小
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
receiveTotal = [[userDefaults objectForKey:@"ReceiveTotal"] doubleValue];
total = [[userDefaults objectForKey:@"Total"] doubleValue];
//顯示上一次下載的進度
if (total > 0) {
CGFloat progress = receiveTotal/total;
self.progressView.progress = progress;
self.progressLabel.text = [NSString stringWithFormat:@"%.2f%%", progress * 100];
}
}
- (IBAction)downLoadClick:(UIButton *)sender {
if (!isDownLoad) {
//1.構建URL
NSURL *url = [NSURL URLWithString:@"http://s.qdcdn.com/lovebizhi/LoveWallpaper4Mac.dmg"];
//2.構建Request
NSMutableURLRequest *mRequest = [NSMutableURLRequest requestWithURL:url];
//斷點續傳
if (receiveTotal > 0) {
//設置續傳位置
NSString *position = [NSString stringWithFormat:@"bytes=%d-",(int)receiveTotal];
[mRequest setValue:position forHTTPHeaderField:@"Range"];
}
//3.發送異步請求
connection = [NSURLConnection connectionWithRequest:mRequest delegate:self];
isDownLoad = YES;
//獲取字符串
NSString *urlStr = url.absoluteString;
//獲取urlStr的最後一部分
NSString *fileName = [urlStr lastPathComponent];
//寫入文件
filePath = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/%@",fileName];
//創建文件
[[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
}
}
//暫停下載
- (IBAction)pauseClick:(UIButton *)sender {
//取消下載連接
[connection cancel];
connection = nil;
//將緩衝數據寫入文件
[self appendFileData:self.receiveData];
//在本地保存已下載文件的大小和文件總大小
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setObject:@(receiveTotal) forKey:@"ReceiveTotal"];
[userDefaults setObject:@(total) forKey:@"Total"];
//將數據同步寫入文件
[userDefaults synchronize];
isDownLoad = NO;
}
#pragma mark-NSURLConnectionDataDelegate
//服務器響應
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response{
self.receiveData = [[NSMutableData alloc]init];
//判斷總大小是否爲0，如果爲0,說明從起始位置開始下，獲取文件總大小
if (total == 0) {
//獲取所有的響應頭
NSDictionary *fields = response.allHeaderFields;
NSLog(@"fields is %@",fields);
//獲取數據的總大小
NSNumber *length = [fields objectForKey:@"Content-Length"];
total = [length doubleValue];
NSLog(@"total is %.2f",total);
}
}
//接收數據
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
[self.receiveData appendData:data];
receiveTotal += data.length;
//計算進度
double progress = receiveTotal / total;
//刷新UI
self.progressView.progress = progress;
self.progressLabel.text = [NSString stringWithFormat:@"%.2f%%",progress * 100];
//判斷緩衝的數據是否大於500KB
if (self.receiveData.length >= 500 * 1024) {
//寫入數據
[self appendFileData:self.receiveData];
//清空
self.receiveData.data = nil;
}
}
//數據傳輸完成
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
//將最後一個緩衝文件寫入
if (self.receiveData.length < 500 * 1024) {
//寫入數據
[self appendFileData:self.receiveData];
//清空
self.receiveData.data = nil;
}
_progressLabel.text = @"下載完成";
self.progressView.progress = 0;
isDownLoad = NO;
}
- (void)appendFileData:(NSData *)data{
if (data.length == 0) {
return;
}
//使用NSFileHandle寫文件，此文件必須已經創建，NSFileHandle不會創建文件
NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:filePath];
//將數據插入到寫入點
[fileHandle seekToEndOfFile];
[fileHandle writeData:data];
//關閉文件，確保寫入完成
[fileHandle closeFile];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}