Swipe after long press - ios

Question

Ok so I am helping convert an android game to iOS. The game is based on 2048, but with letters instead of numbers. I have a good bit of it working but am still learning Objective C/iOS quirks. So far I have the tiles/grid working, movement is working, etc but I need a bit of help. The goal is to allow the user to long-press on a tile to select it, then slide their finger to an adjacent tile to begin spelling a word. I have the long press portion implemented but I'm at a bit of a loss on how to get it to long-press then swipe. On top of this I already have a swipe that allows the user to move the tiles. In searching on here I've seen suggestions about subclassing so I am figuring I need to subclass the UISwipeGestureRecognizer method. I already put in the simultaneously gesture recognizer, but am unsure where to go from here.
So, there are several questions to this.
What would be the best way to do this? Implement a subclass of each UISwipeGestureRecognizer?
Will my current swipe detection interfere? (right now a swipe by itself moves tiles in direction of swipe)
I would guess I need to do a (if long press) then activate subclassed swipe methods?
Any examples to answer the above questions would be of great help. I'm not asking you to do it for me but at least point me in a general direction. Thanks!
Code below.
// Grid.m
#import "Grid.h"
#import "Tile.h"
- (void)didLoadFromCCB {
// listen for swipes to the left
UISwipeGestureRecognizer * swipeLeft= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(swipeLeft)];
swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
[[[CCDirector sharedDirector] view] addGestureRecognizer:swipeLeft];
// listen for swipes to the right
UISwipeGestureRecognizer * swipeRight= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(swipeRight)];
swipeRight.direction = UISwipeGestureRecognizerDirectionRight;
[[[CCDirector sharedDirector] view] addGestureRecognizer:swipeRight];
// listen for swipes up
UISwipeGestureRecognizer * swipeUp= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(swipeUp)];
swipeUp.direction = UISwipeGestureRecognizerDirectionUp;
[[[CCDirector sharedDirector] view] addGestureRecognizer:swipeUp];
// listen for swipes down
UISwipeGestureRecognizer * swipeDown= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(swipeDown)];
swipeDown.direction = UISwipeGestureRecognizerDirectionDown;
[[[CCDirector sharedDirector] view] addGestureRecognizer:swipeDown];
// listen for long press
UILongPressGestureRecognizer *longpress = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:#selector(onLongPress:)];
[longpress setMinimumPressDuration:0.5];
[[[CCDirector sharedDirector] view] addGestureRecognizer:longpress];
}
- (void)swipeLeft {
[self move:ccp(-1, 0)];
}
- (void)swipeRight {
[self move:ccp(1, 0)];
}
- (void)swipeDown {
[self move:ccp(0, -1)];
}
- (void)swipeUp {
[self move:ccp(0, 1)];
}
// detect longpress, convert to NodeSpace and check if touch location is within tile boundingbox. If yes, set background white, text black.
- (void)onLongPress:(UILongPressGestureRecognizer *) recognizer {
CGPoint touchPoint = [[CCDirector sharedDirector] convertToGL:[recognizer locationInView:[recognizer view]]];
touchPoint = [self convertToNodeSpace:touchPoint];
if (recognizer.state == UIGestureRecognizerStateBegan) {
for (Tile *tile in self.children) {
if([tile isKindOfClass:[Tile class]]) {
CGRect tileBoundingBox = tile.boundingBox;
if (CGRectContainsPoint(tileBoundingBox, touchPoint)) {
tile.backgroundNode.color = [CCColor whiteColor];
tile.valueLabel.color = [CCColor blackColor];
[self spellWord:tile.value];
[_word setString:[_word lowercaseString]];
CCLOG(#"%#", _word);
}
}
}
}
if (recognizer.state == UIGestureRecognizerStateChanged) {
}
if (recognizer.state == UIGestureRecognizerStateEnded) {
for (Tile *tile in self.children) {
if([tile isKindOfClass:[Tile class]]) {
CGRect tileBoundingBox = tile.boundingBox;
if (CGRectContainsPoint(tileBoundingBox, touchPoint)) {
tile.backgroundNode.color = [tile getColor:tile.value];
tile.valueLabel.color = [self getContrastColor:r green:g blue:b];
}
}
}
}
}
// allow for simultaneous gestures
- (BOOL)gestureRecognizer:(UIGestureRecognizer *) recognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
return YES;
}

Answer 1

In answer to your questions:
This doesn't strike me as a coding situation that requires one to subclass UILongPressGestureRecognizer. Having said that, subclassing is often a nice way to clean up one's view controller code so you don't have gory gesture recognizer code in the view controller class. But there's nothing here (as I understand it) that demands that. You generally dive into subclassing of gesture recognizers where you need some special custom behavior (e.g. have the gesture fail if some complicated criterion fails). I'd first see if you could achieve the desired UX with standard gestures before I went down that road, though.
The only reason I could see the swipe gestures interfering with each other is that you've specified that shouldRecognizeSimultaneouslyWithGestureRecognizer should return YES. That's used in cases where you need multiple recognizers running at the same, which doesn't seem necessary here (and only a source of problems).
It's unclear to me as to whether you really wanted a separate swipe gesture or whether you just wanted a single gesture ("long press and drag"). If you needed that separate swipe gesture, though, you would generally specify the relative priority of gesture recognizers by specifying requireGestureRecognizerToFail (e.g. have the swipe require long press to fail in order for the swipe to be recognized). But if you really only have one gesture ("long press and drag"), then only one gesture recognizer is needed.
It seems unnecessary. If you want to detect movement after the long press has been recognized, you can put that "move after long press" code in the if statement for UIGestureRecognizedStateChanged in your onLongPress, which occurs after the long press has been recognized, but before the user lifts their finger. The UILongPressGestureRecognizer is a continuous gesture recognizer which will continue to get updates as the user's finger moves after the gesture was initially recognized.
I know you didn't ask for code, but if you wanted a swipe gesture, as well as a long press gesture that was, essentially, the idea of picking it up and dragging it, you could do something like the following. Note, I make the swipe gesture require the long press to fail, so if the user is long pressing, that takes precedence, otherwise it does swipe. But you may not need the swipe gesture at all, so if you don't need it, just remove it altogether:
#import <UIKit/UIGestureRecognizerSubclass.h>
- (void)viewDidLoad {
[super viewDidLoad];
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(handleLongPress:)];
[self.view addGestureRecognizer:longPress];
// if you needed a second gesture, a swipe, completely distinct from the long press and drag
// gesture, you could add it like so:
//
// UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipe:)];
// [swipe requireGestureRecognizerToFail:longPress];
// // do additional swipe configuration
// [self.view addGestureRecognizer:swipe];
}
- (void)handleSwipe:(UISwipeGestureRecognizer *)gesture
{
// do your separate swipe stuff here
}
- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture
{
static UIView *tileToMove;
static CGPoint startCenter;
static CGPoint startLocation;
CGPoint location = [gesture locationInView:self.view];
switch (gesture.state) {
case UIGestureRecognizerStateBegan:
{
// find the tile
tileToMove = [self findTileToMove:location];
if (tileToMove) {
// if found, capture state ...
startCenter = tileToMove.center;
startLocation = location;
// ... and animate "pick up tile", so the user gets positive feedback
// that the drag/swipe portion of the gesture is starting.
[UIView animateWithDuration:0.25 animations:^{
tileToMove.transform = CGAffineTransformMakeScale(1.2, 1.2);
}];
} else {
gesture.state = UIGestureRecognizerStateFailed;
}
break;
}
case UIGestureRecognizerStateChanged:
{
// move the tile as the user's finger moves
CGPoint translate = CGPointMake(location.x - startLocation.x, location.y - startLocation.y);
// note, if you want to constrain the translation to be, for example, on the
// x-axis alone, you could do something like:
//
// CGPoint translate = CGPointMake(location.x - startLocation.x, 0);
tileToMove.center = CGPointMake(startCenter.x + translate.x, startCenter.y + translate.y);
break;
}
case UIGestureRecognizerStateEnded:
{
// animate "drop the tile"
[UIView animateWithDuration:0.25 animations:^{
tileToMove.transform = CGAffineTransformIdentity;
// if you want the tile to "snap" to some location having let it go,
// set the `center` or `frame` here.
}];
// clear our variables, just in case
tileToMove = nil;
startCenter = CGPointZero;
startLocation = CGPointZero;
break;
}
default:
break;
}
}
- (UIView *)findTileToMove:(CGPoint)location
{
for (UIView *tile in self.tiles) {
if (CGRectContainsPoint(tile.frame, location)) {
return tile;
}
}
return nil;
}
This might not be quite the exact UI you're looking for, but it illustrates:
How to have two gestures, where one requires the other to fail in order to establish a precedence between the gestures (and clearly only an issue if you want two distinct gestures, which you probably don't);
To not have shouldRecognizeSimultaneouslyWithGestureRecognizer method because I don't want them both to be recognized simultaneously. Note, that's only needed if you really need two gestures, which you may or may not need; and
How to have a long press that not only recognizes initial long press, but subsequent swipe/drag movement, too.