Uipangesturerecognizer uplink/downlink sliding direction judgment Algorithm

Cgfloat const gestureminimumtranslation = 20.0;

Typedef Enum: nsinteger {

Kcameramovedirectionnone,

Kcameramovedirectionup,

Kcameramovedirectiondown,

Kcameramovedirectionright,

Kcameramovedireleft left

} Cameramovedirection;

@ Interfaceviewcontroller ()

{

Cameramovedirection direction;

}

@ End

@ Implementation viewcontroller

-(Void) viewdidload

{

[Super viewdidload];

Uipangesturerecognizer * recognizer = [[uipangesturerecognizer alloc] initwithtarget: Self action: @ selector (handleswipe :)];

[Self. viewwithgesturerecognizer addgesturerecognizer: recognizer];

}

// This Is My gesture recognizer handler, which detects movement in a particle

// Direction, conceptually tells a camera to start moving in that direction

// And when the user lifts their finger off the screen, tells the camera to stop.

-(Void) handleswipe :( uipangesturerecognizer *) gesture

{

Cgpoint translation = [gesture translationinview: Self. View];

If (gesture. State = uigesturerecognizerstatebegan)

{

Direction = kcameramovedirenone none;

}

Else if (gesture. State = uigesturerecognizerstatechanged & direction = kcameramovedirenone none)

{

Direction = [self determinecameradirectionifneeded: Translation];

// OK, now initiate movement in the direction indicated by the user's gesture

Switch (Direction ){

Case kcameramovedirectiondown:

Nslog (@ "start moving down ");

Break;

Case kcameramovedirectionup:

Nslog (@ "start moving up ");

Break;

Case kcameramovedirectionright:

Nslog (@ "start moving right ");

Break;

Case kcameramovedirectionleft:

Nslog (@ "start moving left ");

Break;

Default:

Break;

}

}

Elseif (gesture. State = uigesturerecognizerstateended)

{

// Now tell the camera to stop

Nslog (@ "stop ");

}

}

// This method will determine whether the direction of the user's swipe

-(Cameramovedirection) determinecameradirectionifneeded :( cgpoint) Translation

{

If (direction! = Kcameramovedirectionnone)

Return direction;

// Determine if horizontal swipe only if you meet some minimum velocity

If (FABS (translation. X)> gestureminimumtranslation)

{

Bool gesturehorizontal = no;

If (translation. Y = 0.0)

Gesturehorizontal = yes;

Else

Gesturehorizontal = (FABS (translation. X/translation. Y)> 5.0 );

If (gesturehorizontal)

{

If (translation. x> 0.0)

Return kcameramovedirectionright;

Else

Return kcameramovedirectionleft;

}

}

// Determine if vertical swipe only if you meet some minimum velocity

Elseif (FABS (translation. Y)> gestureminimumtranslation)

{

Bool gesturevertical = no;

If (translation. x = 0.0)

Gesturevertical = yes;

Else

Gesturevertical = (FABS (translation. Y/translation. X)> 5.0 );

If (gesturevertical)

{

If (translation. Y> 0.0)

Return kcameramovedirectiondown;

Else

Return kcameramovedirectionup;

}

}

Return direction;

}

@ End