I'm trying to improve the responsiveness of my app but am a complete newbie to threading and have become confused.
On launch an alert is shown:
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
if (buttonIndex == 0)
{
NSString *user = [[alertView textFieldAtIndex:0] text];
NSString *pass = [[alertView textFieldAtIndex:1] text];
[self loginToServerWithUsername:user andPassword:pass];
}
}
within the loginToServerWithUsername:
method, the app calls a method:
[self checkFiles:sessionID];
This can take several seconds so I tried to execute it in the background:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self checkFiles:sessionID];
});
checkFiles method:
fileList = [[NSMutableString alloc] init];
NSArray *directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [directoryPaths objectAtIndex:0];
NSString *downloadsFolderString = [documentsDirectory stringByAppendingPathComponent:DOWNLOADS_FOLDER];
NSError *error = nil;
NSString* file;
NSDirectoryEnumerator* enumerator = [[NSFileManager defaultManager] enumeratorAtPath:downloadsFolderString];
while (file = [enumerator nextObject])
{
BOOL isDirectory = NO;
[[NSFileManager defaultManager] fileExistsAtPath: [NSString stringWithFormat:@"%@/%@",downloadsFolderString,file]
isDirectory: &isDirectory];
if (!isDirectory)
{
[fileList appendString:[NSString stringWithFormat:@"%@|", file]];
}
}
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd/MM/yyyy HH:mm"];
NSString *timeOpened = [formatter stringFromDate:[NSDate date]];
NSString *post = [NSString stringWithFormat:@"sessionID=%@&fileList=%@&dateTime=%@&userID=%@", sessionID, fileList, timeOpened, userID];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
NSString *comparisonURLString = SERVER_COMPARE_URL_STRING;
NSURL *comparisonURL = [NSURL URLWithString:comparisonURLString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:comparisonURL];
[request setHTTPMethod:@"POST"];
[request addValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setHTTPBody:postData];
NSHTTPURLResponse *urlResponse = nil;
error = nil;
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&error];
if (responseData)
{
NSString *requiredFilesList = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
NSArray *lines = [requiredFilesList componentsSeparatedByString: @"\n"];
if (lines.count > 2)
{
dispatch_async(dispatch_get_main_queue(), ^(void){
NSRange theRange;
theRange.location = 2;
theRange.length = [lines count] -3;
numberOfFilesToBeDownloaded = theRange.length;
if (numberOfFilesToBeDownloaded <= 0)
{
_jobStatusLabel.text = @"Documents up to date"; // is this the issue?
}
if (numberOfFilesToBeDownloaded > 0)
{
NSArray *subArray = [lines subarrayWithRange:theRange];
[self animateProgressBar];
if (![eraseDevice isEqualToString:@"true"])
{
[self getFiles:subArray];
}
}
});
}
}
else
{
NSLog(@"no response data from check files");
}
However, the alertView
is not dismissed until the checkFiles
method is complete.
Can anyone tell me how to have the alert dismiss whilst checkFiles
runs in the background?