Calling a function delayed in objective-c without a 2nd thread

I want to call a function, that is sending a sentence, delayed, in order to simulate a stream of data. The data is stored in a textfile. Each line of the textfile contains one sentence. I tried to get a delayed calling behaviour earlier by using sleep(x) but this freezed the whole application. Do I have to use a seperate thread or is it possible to get it working with NSTimer or sth. like [self performSelector:@selector(parseSentence:) withObject:s afterDelay:2] ?

- (void) simulateStream
{
    NSArray *sentences;


NSString *path = [[NSBundle mainBundle] pathForResource:@"Sentence_File" ofType:@"txt"];
NSString *st;

if (path) 
{
st=[NSString stringWit开发者_C百科hContentsOfFile:pfad 
    encoding:NSUTF8StringEncoding 
    error:nil];

sentences=[[st substringFromIndex:[st rangeOfString:@"$"].location+1]
componentsSeparatedByString:@"$"];  
}

for(int i=0; i<[sentences count]; i++) 
{
    //----CALL THIS WITH A DELAY OF 2 SECONDS----
[sentenceHandler parseSentence:[sentences objectAtIndex:i]]; 

}}

Thanks for help. Greetings

You could increase the delay interval in each pass:

NSTimeInterval delay = 2;
for (NSString* sentence in sentences) {
   [sentenceHandler performSelector:@selector(parseSentence:)
                         withObject:sentence
                         afterDelay:delay];
   delay += 2;
}