simple stretch

ViewController.m

//
//  ViewController.m
//  stretch
//
//  Created by MizushimaYusuke on 8/7/15.
//  Copyright (c) 2015 MizushimaYusuke. All rights reserved.
//

#import "ViewController.h"
@import SceneKit;

@interface ViewController ()
@property (nonatomic, weak) SCNView *sceneView;
@end

@implementation ViewController

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

- (void)setupScene {
    SCNView *sv = [[SCNView alloc] initWithFrame:self.view.bounds];
    sv.backgroundColor = [UIColor colorWithHue:0.5 saturation:0.4 brightness:0.9 alpha:1];
    sv.scene = [SCNScene scene];
    sv.allowsCameraControl = YES;
    [self.view addSubview:sv];
    
    self.sceneView = sv;
}

- (void)createBar {
    float rate = 3;
    for (int i=0; i<20; i++) {
        float x = (arc4random() % 10) * rate;
        float y = (arc4random() % 10) * rate;
        float z = (arc4random() % 10) * rate;
        
        SCNBox *bar = [SCNBox boxWithWidth:5 height:0.5 length:0.5 chamferRadius:0];
        bar.firstMaterial.diffuse.contents = [UIColor whiteColor];
            
        SCNNode *barNode = [SCNNode nodeWithGeometry:bar];
        barNode.position = SCNVector3Make(x, y, z);
        [self.sceneView.scene.rootNode addChildNode:barNode];
        
        float delay = (arc4random() % 3) * 0.5;
        
        SCNAction *(^expandX)(float) = ^(float w){
            return [SCNAction customActionWithDuration:1.0 actionBlock:^(SCNNode *node, CGFloat elapsedTime) {
                node.scale = SCNVector3Make(w * elapsedTime + 1, 1, 1);
            }];
        };
        
        NSArray *actions = @[expandX(0.8), [SCNAction scaleTo:1 duration:1.0]];
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delay * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [barNode runAction:[SCNAction repeatActionForever:[SCNAction sequence:actions]]];
        });
    }
}

@end

blog : http://lepetit-prince.net/ios/?p=4222