Rotating uiimageview moves image back to original storyboard position

Question

I am using the accelerometer to move an image (helicopter) around the screen. I'm trying to add code so when the helicopter moves forward it rotates the uiimageview by 20 degrees, when the helicopter moves backwards it rotates the uiimageview by -20 degrees, the idea being to create the effect that the helicopter moves more realistically. However, when the rotation is applied the uiimageview moves back to its original starting position (the position I have placed it in the story bard). Any ideas why? Here's the code:

-(void)outputAccelerationData:(CMAcceleration)acceleration

{
if (helicoptervalueX>1.5){
    helicopterrotation = 1;
   helicopter.transform = CGAffineTransformRotate(CGAffineTransformIdentity,0.34906585 ); 
    NSLog(@"Tilt forward");
} else if (helicoptervalueX < -1.5){
    helicopterrotation = -1;
     helicopter.transform = CGAffineTransformRotate(CGAffineTransformIdentity, -0.34906585);    
    NSLog(@"Tilt backward");}
else if (helicoptervalueX<=1.5 && helicoptervalueX>=-1.5){
    helicopterrotation = 0;
     helicopter.transform = CGAffineTransformRotate(CGAffineTransformIdentity, 0);
    NSLog(@"Helicopter flat");}




helicoptervalueX = -(acceleration.y*50.0)+calibrationx;
helicoptervalueY = (acceleration.x*50.0)+calibrationy;



int helicopternewX = (int)(helicopter.center.x + helicoptervalueX);

if (helicopternewX > 518) {
    helicopternewX = 518;}

if (helicopternewX < 50){
    helicopternewX = 50;}

int helicopternewY = (int)(helicopter.center.y - helicoptervalueY);

if (helicopternewY > 295){
    helicopternewY = 295;}


if (helicopternewY < 25){
    helicopternewY = 25;}

CGPoint helicopternewCenter = CGPointMake(helicopternewX, helicopternewY);

helicopter.center = helicopternewCenter;

}

score 0 · Answer 1 · answered Apr 11 '14 at 09:25

Did you try this ? To preserve the existing transform and apply rotation on top of it :

   helicopter.transform = CGAffineTransformRotate([helicopter transform],angle );

Then to go back to horizontal, you will probably have to apply the negative angle:

   helicopter.transform = CGAffineTransformRotate([helicopter transform], -angle );

Rotating uiimageview moves image back to original storyboard position

1 Answers1