Placing an NSTimer in a separate thread

Question

Note: It\'s probably worth scrolling down to read my edit.

I\'m trying to setup an NSTimer in a separate thread so that it continues to fire when us

Answer 1

If the only reason you are spawning a new thread is to allow your timer to run while the user is interacting with the UI you can just add it in different runloop modes:

NSTimer *uiTimer = [NSTimer timerWithTimeInterval:(1.0 / 5.0) target:self selector:@selector(uiTimerFired:) userInfo:nil repeats:YES];      
[[NSRunLoop mainRunLoop] addTimer:uiTimer forMode:NSRunLoopCommonModes];

As an addendum to this answer it is now possible to schedule timers using Grand Central Dispatch and blocks:

// Update the UI 5 times per second on the main queue
// Keep a strong reference to _timer in ARC
_timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
dispatch_source_set_timer(_timer, DISPATCH_TIME_NOW, (1.0 / 5.0) * NSEC_PER_SEC, 0.25 * NSEC_PER_SEC);

dispatch_source_set_event_handler(_timer, ^{
    // Perform a periodic action
});

// Start the timer
dispatch_resume(_timer);

Later when the timer is no longer needed:

dispatch_source_cancel(_timer);