Using NSTimer with two intervals - objective-c

Question

I'm creating an app that converts text to Morse code, and then flash it out using the iPhone's flashlight. I have used string replacement, to convert the content of a NSString to Morse code.
// some of the code :
str = [str stringByReplacingOccurrencesOfString:#"5" withString:n5];
str = [str stringByReplacingOccurrencesOfString:#"6" withString:n6];
str = [str stringByReplacingOccurrencesOfString:#"7" withString:n7];
str = [str stringByReplacingOccurrencesOfString:#"8" withString:n8];
str = [str stringByReplacingOccurrencesOfString:#"9" withString:n9];
str = [str stringByReplacingOccurrencesOfString:#"0" withString:n0];
NSString *morseCode = [[NSString alloc] initWithFormat:str];
self.label.text = morseCode;
I have found a script that turns the iPhone's flashlight on and off, with adjustable intervals using NSTimer. But I can't figure out how to add two different intervals, one for the dot and one for the Morse dash.
- (void)viewDidLoad
{
[super viewDidLoad];
int spaceTime;
spaceTime = 1;
int dashTime;
dashTime = 2;
int dotTime;
dotTime = 0.8;
strobeIsOn = NO;
strobeActivated = NO;
strobeFlashOn = NO;
flashController = [[FlashController alloc] init];
self.strobeTimer = [
NSTimer
scheduledTimerWithTimeInterval:spaceTime
target:self
selector:#selector(strobeTimerCallback:)
userInfo:nil
repeats:YES
];
self.strobeFlashTimer = [
NSTimer scheduledTimerWithTimeInterval:dotTime
target:self
selector:#selector(strobeFlashTimerCallback:)
userInfo:nil
repeats:YES
];
}
- (void)strobeTimerCallback:(id)sender {
if (strobeActivated) {
strobeIsOn = !strobeIsOn;
// ensure that it returns a callback. If no, returns only one flash
strobeFlashOn = YES;
} else {
strobeFlashOn = NO;
}
}
- (void)strobeFlashTimerCallback:(id)sender {
if (strobeFlashOn) {
strobeFlashOn = !strobeFlashOn;
[self startStopStrobe:strobeIsOn];
} else {
[self startStopStrobe:NO];
}
}
Should I use two timers or can I have one with different intervals? Should I put the content of the string in an array?
I'm new in Obj-C ..

Answer 1

I would try to make a recursive function:
parseAndFlash
{
NSString *codeString = #"-.-. --- -.. .";
int currentLetterIndex = 0;
//codeString and currentLetterIndex should be declared outside this function as members or something
double t_space = 2, t_point = 0.5, t_line = 1, t_separator = 0.1;
double symbolDuration = 0;
if(currentLetterIndex >= [codeString length])
return;
char currentLetter = [codeString characterAtIndex:currentLetterIndex];
switch (currentLetter) {
case '-':
symbolDuration = t_line;
[self flashOnFor:t_line];
break;
case '.':
symbolDuration = t_point;
[self flashOnFor:t_point];
break;
case ' ':
symbolDuration = t_space;
[self flashOff];
break;
default:
break;
}
currentLetterIndex ++;
symbolDuration += t_separator;
[self performSelector:#selector(parseAndFlash) withObject:nil afterDelay:symbolDuration];
}

Answer 2

you can try to run code in sequence on background treed and sleep it for as long as you need. It would be much easier code to write and maintain than to use bunch of timers.
// execute in background
[self performSelectorInBackground:#selector(doTheMagic) withObject:nil];
- (void)doTheMagic {
NSLog(#"Turn ON");
[NSThread sleepForTimeInterval:1];
NSLog(#"Turn OFF");
[NSThread sleepForTimeInterval:0.1f];
NSLog(#"Turn ON");
[NSThread sleepForTimeInterval:1.0f];
// ...
}