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The correct way to display downloadable content in a UITableView (using ProgressBar, etc.)

I think this is a pretty tricky question. I have a TableView that displays several downloadable materials. When you click on the button in the cell, the download starts.

But I have a few questions: 1. How can I make sure that the progressBar will be displayed all the time (even if the user scrolls the scrolls and the cell will be reloaded) 2. How can I make sure that the user can download 2 files at once. I am afraid this is causing problems because I am using some instance variables. In a way, it should work a bit with iCloud in a music app.

Here is my code

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:nil];   
    }
    //cell.tag = indexPath.row*10;
    Uebungsblaetter *uebungCell = [uebungsblattArray objectAtIndex:indexPath.row];
    cell.tag = indexPath.row*10;
    cell.textLabel.text = [self getFileNameOutOf:uebungCell.url];
    cell.textLabel.textColor = [UIColor grayColor];
    cell.selectionStyle = UITableViewCellSelectionStyleNone;
    UIButton *dl = [UIButton buttonWithType:UIButtonTypeCustom];
    dl.tag = indexPath.row*10;
    [dl setBackgroundImage:[UIImage imageNamed:@"downloadButton.png"] forState:UIControlStateNormal];
    [dl setBackgroundImage:[UIImage imageNamed:@"downloadButtonH.png"] forState:UIControlStateHighlighted];
    [dl setFrame:CGRectMake(230.0, (cell.frame.size.height-28)/2, 28, 28)];
    [dl addTarget:self action:@selector(downloadFileWhenPressedButton:) forControlEvents:UIControlEventTouchUpInside];
    [cell.contentView addSubview:dl];
    UIProgressView *dlProgress = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
    dlProgress.frame = CGRectMake(cell.frame.size.width-150, 17, 50, 9);
    dlProgress.tag =indexPath.row*10+1;
    dlProgress.progress = 0.0;
    [cell.contentView addSubview:dlProgress];
    [dlProgress setHidden:YES];   

    return cell;
}

//download methods
- (void)downloadFileWhenPressedButton:(UIButton*)sender{
    sender.hidden = YES;
    dlIndex = sender.tag/10;
    Uebungsblaetter *selectedUB = [uebungsblattArray objectAtIndex:dlIndex];
    NSURL *theUrl = [NSURL URLWithString:selectedUB.url];
    NSURLRequest *req=[NSURLRequest requestWithURL:theUrl cachePolicy:NSURLCacheStorageNotAllowed timeoutInterval:120];
    dlCell = (UITableViewCell *)[[sender superview]superview];
    currDlProgress = (UIProgressView* )[dlCell.contentView viewWithTag:dlIndex*10+1];
    currDlProgress.hidden = NO;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    dlFilePath = [NSString stringWithFormat:@"%@/%@_%@", [paths objectAtIndex:0],self.courseLable.text,[self getFileNameOutOf:selectedUB.url]];
    NSURLConnection *con=[[NSURLConnection alloc] initWithRequest:req delegate:self startImmediately:YES];
    if (con) {
        myWebData = [NSMutableData data];
    }

}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
    UIApplication* app = [UIApplication sharedApplication];
    app.networkActivityIndicatorVisible = YES;
    currDlProgress.progress = 0;
    _totalFileSize = response.expectedContentLength;
    NSLog(@"%@",@"connection established");
    [myWebData setLength: 0];



}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    _receivedDataBytes += [data length];
    currDlProgress.progress = _receivedDataBytes / (float)_totalFileSize;

    NSLog(@"%@",@"connection receiving data");
    [myWebData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"%@",@"connection failed");
    //  [AlertViewHandler showAlertWithErrorMessage:@"Sorry, there is no network connection. Please check your network and try again."];
    //  [self parserDidEndDocument:nil];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    UIApplication* app = [UIApplication sharedApplication];
    app.networkActivityIndicatorVisible = NO;
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.35];
    [currDlProgress setAlpha:0];
    [UIView commitAnimations];
    [myWebData writeToFile:dlFilePath atomically:YES];
    Uebungsblaetter *loadedUB = [uebungsblattArray objectAtIndex:dlIndex];
    loadedUB.downloaded = [NSNumber numberWithBool:YES];
    [courseTable reloadData];
}

It would be nice if someone had a key or a good code example

+5
2

, (.. , , , ). - , , . , , , , , , .

- . NSMutablerray, NSMutableDictionary, .

@property (nonatomic, strong) NSMutableArray *activeConnections;

viewDidLoad::

- (void)viewDidLoad
{
    [super viewDidLoad];
    //...

    self.activeConnections = [[NSMutableArray alloc] init];
}

, , NSMutableDictionary , .

- (void)downloadFileWhenPressedButton:(UIButton*)sender
{
    // ...

    //  then create dictionary
    NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
    [dict setObject:con forKey:@"connection"];  // save connection so we can reference later
    [dict setObject:[NSNumber numberWithInt:[sender.tag]/10] forKey:@"row"];  // this is the row index from your table
    [dict setObject:[NSNumber numberWithInt:999] forKey:@"totalFileSize"];  // dummy size, we will update when we know more
    [dict setObject:[NSNumber numberWithInt:0] forKey:@"receivedBytes"];

    [self.activeConnections addObject:dict];
}

, , , .

- (NSDictionary*)getConnectionInfo:(NSURLConnection*)connection
{
    for (NSDictionary *dict in self.activeConnections) {
        if ([dict objectForKey:@"connection"] == connection) {
            return dict;
        }
    }
    return nil;
}

- (NSDictionary*)getConnectionInfoForRow:(int)row
{
    for (NSDictionary *dict in self.activeConnections) {
        if ([[dict objectForKey:@"row"] intValue] == row) {
            return dict;
        }
    }
    return nil;
}

,  

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    // ...

    NSDictionary *dict = [self getConnectionInfo:connection];
    [dict setObject:[NSNumber numberWithInt:response.expectedContentLength] forKey:@"totalFileSize"];
}

, , tableView , .

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    // ...

    NSDictionary *dict = [self getConnectionInfo:connection];
    NSNumber bytes = [data length] + [[dict objectForKey:@"receivedBytes"] intValue];

    [dict setObject:[NSNumber numberWithInt:response.expectedContentLength] forKey:@"receivedBytes"];

    int row = [[dict objectForKey:@"row"] intValue];
    NSIndexPath *indexPath = [NSIndexPathindexPathForRow:row inSection:0];
    [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] 
                          withRowAnimation:UITableViewRowAnimationNone];
}

, activeConnections .

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{
    // ...

    NSDictionary *dict = [self getConnectionInfo:connection];
    [self.activeConnections removeObject:dict];

    int row = [[dict objectForKey:@"row"] intValue];
    NSIndexPath *indexPath = [NSIndexPathindexPathForRow:row inSection:0];
    [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] 
                          withRowAnimation:UITableViewRowAnimationNone];
}

, cellForRowAtIndexPath: activeConnections.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // ...

    // remove any previous buttons or progress bars from this cell
    for (UIView *view in [cell.contentView subViews]) {

        if ([view isKindOfClass:[UIProgressView class]] || [view isKindOfClass:[UIButton class]]) {
            [view removeFromSuperView];
        }
    }

    // look for active connecton for this cell
    NSDictionary *dict = [self getConnectionInfoForRow:indexPath.row];

    if (dict) {
        // there is an active download for this cell, show a progress bar

        UIProgressView *dlProgress = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
        dlProgress.frame = CGRectMake(cell.frame.size.width-150, 17, 50, 9);
        dlProgress.tag = indexPath.row*10+1;
        dlProgress.progress = [[dict objectForKey:@"receivedBytes"] intValue] / [[dict objectForKey:@"totalFileSize"] intValue];

        [cell.contentView addSubview:dlProgress];

    } else {
        // no active download, show the download button

        UIButton *dl = [UIButton buttonWithType:UIButtonTypeCustom];
        dl.tag = indexPath.row*10;
        [dl setBackgroundImage:[UIImage imageNamed:@"downloadButton.png"] forState:UIControlStateNormal];
        [dl setBackgroundImage:[UIImage imageNamed:@"downloadButtonH.png"] forState:UIControlStateHighlighted];
        [dl setFrame:CGRectMake(230.0, (cell.frame.size.height-28)/2, 28, 28)];
        [dl addTarget:self action:@selector(downloadFileWhenPressedButton:) forControlEvents:UIControlEventTouchUpInside];
        [cell.contentView addSubview:dl];
    }
}
+20

, . , , . , , (, bool, , , , ..). , objectAtIndex:0 - ..

. , , NSKeyValueObserving, , . , , , , , , , .

, - .

+3

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