I want to use the following:
class func sleepForTimeInterval(_ ti: NSTimeInterval)
It is a NSTimer function that I found here. I cant figure out how and where to declare the function. I want a 0.1s delay before executing another function.
If you want to do something after 0.1, you can probably try this code:
double delayInSeconds = 0.1;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
// do something after delay
});
For beginner, it's the best if you can go check out the documentation. Here is the link about NSTimer: https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSTimer_Class/index.html
And I don't think you can do something like what you said by using NSTimer.
Related
I got stuck in a problem. I'm trying to run a timer in a method which itself is in background resulting my timer is not initiating. I got to know some where that timer can't be initialized in background so is there any way to do this?
You can perform the operation on main thread.
[self performSelectorOnMainThread:#selector(initTimer) withObject:nil waitUntilDone:NO];
and then
- (void)initTimer {
// Init your timer here.
}
You can try Background Fetch in ios7 to run code on background
Try this :
// provide value as required. Time here is 3 sec
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, 3.0 * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
// do your task
});
As pointed out by #Bryan Chen, you can schedule a method to be run on the current thread using the following code:
dispatch_time_t when = dispatch_time(DISPATCH_TIME_NOW, 0.3 * NSEC_PER_SEC);
dispatch_after(when, dispatch_get_current_queue(), ^(void) {
[self myTimedMethod];
});
You cannot use NSTimer in a background thread unless you are maintaining a run loop on that thread.
I want to call a method after certain time.
This is just an example.
- (void)myMethod:(int)value1 setValue2:(CGPoint)value2{
//Do Something with values
}
At first I thought
[self scheduleOnce:#selector(myMethod:setValue2:) delay:timeToWait];
but I can't pass the arguments when using selector, so Im asking you guys for an alternative...What could I do?
Thanks for your time guys and have a great day!
You can try GCD's dispatch_after. For instance:
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
[self myMethod:someValue setValue2: someValue2];
});
You could put your arguments into an NSDictionary and pass that as the object parameter to - (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay
I'd like to pop a display from inside a completion block, but I also want to dismissModalViewControllerAnimated from inside the same block (but AFTER the popup completes). Note that the popup schedules and runs after the completion block execution finishes, which means it never happens since the dismissal is synchronous...
So, a quick fix would be to find a way to schedule the dismissal asynchronously for after the popup. Is there a chaining method? A way to force holding async tasks to run and wait for them?
Use -performSelector:withObject:afterDelay:. You'll need to wrap the dismissal in a selector matching the signature required by -performSelector:..., since dismissModalViewControllerAnimated: takes a BOOL.
You can use dispatch_after instead, and it will be dismissed animatedly. check this simple sample code:
int64_t delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
[self dismissModalViewControllerAnimated:YES];
});
I have a need to delay for a certain amount of time and yet allow other things on the same runloop to keep running. I have been using the following code to do this:
[[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:1]];
This seems to do exactly what I want, except that sometimes the function returns immediately without waiting the desired time (1 second).
Can anyone let me know what could cause this? And what is the proper way to wait while allowing the run loop to run?
NOTE: I want to delay in a manner similar to sleep(), such that after the delay I am back in the same execution stream as before.
You should use GCD and dispatch_after for that. It is much more recent and efficient (and thread-safe and all), and very easy to use.
There is even a code snippet embedded in Xcode, so that if you start typing dispatch_after it will suggest the snippet and if you validate it will write the prepared 2-3 lines for you in your code :)
int64_t delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
<#code to be executed on the main queue after delay#>
});
Use an NSTimer to fire off a call to some method after a certain delay.
Have you tried performSelector:withObject:afterDelay:?
From the Apple documentation
Invokes a method of the receiver on the current thread using the default mode after a delay.
I had a similar issue and this is my solution. Hope it works for others as well.
__block bool dispatched = false;
while ( put your loop condition here )
{
if (dispatched)
{
// We want to relinquish control if we are already dispatched on this iteration.
[ [ NSRunLoop currentRunLoop ] runMode: NSDefaultRunLoopMode beforeDate:[ NSDate date ] ];
continue;
}
// mark that a dispatch is being scheduled
dispatched = true;
int64_t delayInNanoSeconds = (int64_t) (0.1 * (float) NSEC_PER_SEC);
dispatch_time_t delayTime = dispatch_time(DISPATCH_TIME_NOW, delayInNanoSeconds);
dispatch_after(delayTime, dispatch_get_main_queue(), ^() {
// Do your loop stuff here
// and now ready for the next dispatch
dispatched = false;
} );
} // end of while
It is easy to delay executing something like this
double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
<#code to be executed on the main queue after delay#>
});
But it will make above code fail to execute if putting another longer delay like
double delayInSeconds2 = 3.0;
dispatch_time_t popTime2 = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds2 * NSEC_PER_SEC);
dispatch_after(popTime2, dispatch_get_main_queue(), ^(void){
<#code to be executed on the main queue after delay#>
});
Why just execute the longer one instead of both ? Or am I totally wrong ?
it is a queue, but the position depend on the future fire time instead of enqueue time.
if second one is 1 second, it will be insert before the first one.
if you want them executed concurrently (time slice for single core or real concurrency for multi-core cpu), put them on different queue.