How to move sprite from right to left of screen using CGPathAddArc - path

Question

my sprite position is (screenWidth, screenHeigh/2). i have tried a lot of code which using CGPathAddArc to move sprite from right to left but not success. apple document is so hard to understand. so i post here with a hope someone can help me.
this is one of the code i had used.
if (iPad) {
CGPathAddArc(thePath, NULL, 384.0f , 768, 384.0f , 0.f, -M_PI*3/2, NO);
}
SKAction *moveAction = [SKAction followPath:thePath asOffset:YES orientToPath:NO duration:(5.0f/200.0f)*(iPad ? 384.0f :200.f)];
many thank in advance

Answer 1

If you create a blank SpriteKit project, this slightly modified default code for GameScene.m will make the spaceship fly through from right to left following a half-circle path.
Pls comment if you need further clarification!
Key difference from your code snippet that for [SKAction followPath...] the asOffset parameter is NO, and the orientToPath is YES.
#import "GameScene.h"
#implementation GameScene
-(void)didMoveToView:(SKView *)view {
/* Setup your scene here */
SKLabelNode *myLabel = [SKLabelNode labelNodeWithFontNamed:#"Chalkduster"];
myLabel.text = #"Hello, World!";
myLabel.fontSize = 65;
myLabel.position = CGPointMake(CGRectGetMidX(self.frame),
CGRectGetMidY(self.frame));
[self addChild:myLabel];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
/* Called when a touch begins */
for (UITouch *touch in touches) {
CGPoint location = [touch locationInNode:self];
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithImageNamed:#"Spaceship"];
sprite.xScale = 0.5;
sprite.yScale = 0.5;
sprite.position = location;
// HERE COMES THE MODIFICATION
CGMutablePathRef thePath = CGPathCreateMutable();
CGPathAddArc(thePath, NULL, self.frame.size.width/2 , 200, self.frame.size.width/2 , 0.f, -M_PI, NO);
SKAction *moveAction = [SKAction followPath:thePath asOffset:NO orientToPath:YES duration:5.0];
[sprite runAction:[SKAction repeatActionForever:moveAction]];
// HERE ENDS THE MODIFICATION
[self addChild:sprite];
}
}
-(void)update:(CFTimeInterval)currentTime {
/* Called before each frame is rendered */
}
#end
Hope this helps!