u curve

ViewController.m

//
//  ViewController.m
//  UCurve
//
//  Created by MizushimaYusuke on 2017/04/22.
//  Copyright © 2017 MizushimaYusuke. All rights reserved.
//

#import "ViewController.h"
@import SpriteKit;

@interface ViewController ()
@property (nonatomic, weak) SKScene *scene;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setupScene];
    [self createPattern];
}

- (void)setupScene {
    SKView *sv = [[SKView alloc] initWithFrame:self.view.bounds];
    SKScene *s = [SKScene sceneWithSize:sv.frame.size];
    s.backgroundColor = [UIColor darkGrayColor];
    [sv presentScene:s];
    [self.view addSubview:sv];
    self.scene = s;
}

- (void)createPattern {
    for (int i=0; i<12; i++) {
        for (int j=0; j<8; j++) {
            SKNode *u = [self createU];
            u.name = @"u";
            u.position = CGPointMake(i * 70, j * 70);
            [self.scene addChild:u];
        }
    }
}

- (SKNode *)createU {
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(2.5, 0)];
    [path addLineToPoint:CGPointMake(2.5, 35)];
    [path addArcWithCenter:CGPointMake(20, 35) radius:17.5 startAngle:M_PI endAngle:0 clockwise:NO];
    [path addLineToPoint:CGPointMake(37.5, 0)];
    
    path.lineWidth = 5;
    
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(40, 60), false, 0);
    [[UIColor colorWithHue:0.2 saturation:0.7 brightness:1 alpha:1] set];
    [path stroke];
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    SKTexture *texture =[SKTexture textureWithImage:img];
    SKSpriteNode *u = [SKSpriteNode spriteNodeWithTexture:texture];
    return u;
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self.scene enumerateChildNodesWithName:@"u" usingBlock:^(SKNode * _Nonnull node, BOOL * _Nonnull stop) {
        float w = arc4random_uniform(10);
        [node runAction:[SKAction rotateByAngle:M_PI * 0.25 * w duration:1.0]];
    }];
}

@end

http://lepetit-prince.net/ios/?p=6201