Updating the UI control's value in the runtime from background thread. - multithreading

Question

I know this sound a very simple question. I'm still a newbie in iPad app development. Would you please tell me how would I update the contents in the run time. The following code may be helpful to know my question in detail.
In the following code, I'm trying to display text contents in the TexViewcontrol. When I change the for loop form 10 to 100000, I needed to wait until everything fills up. I need to display the contents on the screen while loop is running.
- (IBAction)RunHelloWorld:(id)sender
{
tctView.text = #"tt";
for(int i=0;i<10;i++)
{
NSString *result1 = #"Testing";
tctView.text = [tctView.text stringByAppendingString:result1];
tctView.scrollEnabled = YES;
}
}
Would you please give me any help? Thanks a LOT!!!
-Teva

Answer 1

Finally I found the solution with the following URL's help. http://samplecodebank.blogspot.com/2011/05/nsthread-example_12.html
Thanks a LOT!
This is my code.
PCViewController.h file code
#import <UIKit/UIKit.h>
#interface PCViewController : UIViewController
{
IBOutlet UITextView *txtView;
}
-(void)ReadFile;
- (void) mainThreadSetText:(NSString*)text;
#end
PCViewController.m file code
#import "PCViewController.h"
#interface PCViewController ()
#end
#implementation PCViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[NSThread detachNewThreadSelector:#selector(ReadFile) toTarget:self withObject:nil];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
-(void)ReadFile
{
// Check whether current thread is externally terminated or not.
char line[1024];
FILE *fp = fopen("/Users/Teva/Desktop/File1.txt","r");
while([[NSThread currentThread] isCancelled] == NO)
{
if( fp != NULL )
{
while( fgets(line,1024,fp) )
{
printf("%s\n",line);
NSString *result1 = [NSString stringWithCString:line encoding:NSASCIIStringEncoding];
[self performSelectorOnMainThread:#selector(mainThreadSetText:) withObject:result1 waitUntilDone:YES];
[NSThread sleepForTimeInterval:1.0];
}
}
}
}
// Screen processing should be done outside the Thread.
- (void) mainThreadSetText:(NSString*)text
{
txtView.text = [txtView.text stringByAppendingString:text];
txtView.scrollEnabled = YES;
}
- (void)dealloc
{
[txtView release];
[super dealloc];
}
#end