UIButton press and hold - repeat action until let go - ios

Question

I want to have a certain method run and repeat itself for as long as someones finger is pressed down on a button. I want that method to stop repeating itself when the finger is not on the button anymore
Is there a way to check if the touchDown is still occurring during the method implementation? Help!

Answer 1

You can use the UIControlEventTouchDown control event to start the method running, and UIControlEventTouchUpInside, or similar, to detect when the button is no longer being "pressed".
Set up the actions to the button, e.g.:
[myButton addTarget:self action:#selector(startButtonTouch:) forControlEvents:UIControlEventTouchDown];
[myButton addTarget:self action:#selector(endButtonTouch:) forControlEvents:UIControlEventTouchUpInside | UIControlEventTouchUpOutside];
(Note the above will cause touch up inside and outside the button to invoke the endButtonTouch: method.)
Then add the startButtonTouch: and endButtonTouch methods, e.g., :
- (void)startButtonTouch:(id)sender {
// start the process running...
}
- (void)endButtonTouch:(id)sender {
// stop the running process...
}

Answer 2

Drawing upon the bobnoble's answer here's a helper view
#import <UIKit/UIKit.h>
#interface YOIDCAutorepeatingButton : UIButton
// you COULD pinch pennies switching to nonatomic, but consider
// how much time it would take to debug if some day some moron decides without checking this spec
// to alter this prop off another thread
#property (atomic) NSTimeInterval delayUntilAutorepeatBegins;
#property NSTimeInterval delayBetweenPresses;
#property (weak) id<NSObject> recipient;
#property SEL touchActionOnRecipient;
#end
-------------> .m
#import "YOIDCAutorepeatingButton.h"
#interface YOIDCAutorepeatingButton()
{
NSTimeInterval _pressStartedAt;
}
#end
#implementation YOIDCAutorepeatingButton
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self) {
[self addTarget:self action:#selector(startButtonTouch:) forControlEvents:UIControlEventTouchDown];
[self addTarget:self action:#selector(endButtonTouch:) forControlEvents:UIControlEventTouchUpInside | UIControlEventTouchUpOutside];
self.delayUntilAutorepeatBegins = .250;
self.delayBetweenPresses = .080;
}
return self;
}
-(void)killLastCharacter:(id)sender
{
[self.recipient performSelector:self.touchActionOnRecipient withObject:sender];
}
- (void)performAutorepeat:(id)sender
{
if(!self.delayBetweenPresses) {
// bail
return;
}
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(self.delayBetweenPresses * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
if(_pressStartedAt) {
[self killLastCharacter:sender];
[self performAutorepeat:sender];
}
});
}
- (void)startButtonTouch:(id)sender {
[self killLastCharacter:sender];
NSTimeInterval now = [NSDate timeIntervalSinceReferenceDate];
_pressStartedAt = now;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(self.delayUntilAutorepeatBegins * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
if(_pressStartedAt) {
[self killLastCharacter:sender];
[self performAutorepeat:sender];
}
});
}
- (void)endButtonTouch:(id)sender {
_pressStartedAt = 0;
}
#end
-------- sample usage -------
- (IBAction)killLastDigit:(id)sender {
.....
- (void)viewDidLoad
{
assert(self.backSpace);
[YOIDCAutorepeatingButton class]; // if xib is in a bundle other than main gottal load the class
// otherwise you'd get -[UIButton setRecipient:]: unrecognized selector sent to instance
// on setRecipient:
self.backSpace.recipient = self;
self.backSpace.touchActionOnRecipient = #selector(killLastDigit:);