Infinite Equilateral Triangle Animation as Activity Indicator

EYInfiniteEquilateralTriangleAnimationView.h

// erkanyildiz
// 20150813-1940
//
// EYInfiniteEquilateralTriangleAnimationView.h

#import <UIKit/UIKit.h>

@interface EYInfiniteEquilateralTriangleAnimationView : UIView
- (instancetype) initWithSide:(CGFloat)side andCenter:(CGPoint)center;
- (void) start;
@end

EYInfiniteEquilateralTriangleAnimationView.m

// erkanyildiz
// 20150813-1940
//
// EYInfiniteEquilateralTriangleAnimationView.m

#import "EYInfiniteEquilateralTriangleAnimationView.h"

@interface EYInfiniteEquilateralTriangleAnimationView ()
{
    UIView* tUp;
    UIView* tLeft;
    UIView* tRight;
    UIView* tCenter;
    NSArray* minors;
    
    CGFloat _side;
    
    #define DURA 4.0
    #define SCALE 2.0
    #define SHRINK 0.3

    #define D2R(angle) ((angle) * M_PI / 180.0)
}
@end

@implementation EYInfiniteEquilateralTriangleAnimationView
-(instancetype) initWithSide:(CGFloat)side andCenter:(CGPoint)center
{
    _side = side;
    
    CGFloat containerSide = side * 2 * sqrt(3) / 3.0;
    typeof(self) infiniteTriangle = [self initWithFrame:(CGRect){center.x - containerSide * 0.5 , center.y - containerSide * 0.5, containerSide, containerSide}];
    
    CGFloat minorTriangleSide = side * 0.5;
    
    CGPoint cUp = (CGPoint){containerSide * 0.5, minorTriangleSide * 0.5 * 2 * sqrt(3) / 3.0};
    
    CGPoint cLeft = cUp;
    cLeft.x -= minorTriangleSide * 0.5;
    cLeft.y += minorTriangleSide * 0.5 * sqrt(3);
    
    CGPoint cRight = cLeft;
    cRight.x += minorTriangleSide;
    
    CGPoint cCenter = (CGPoint){containerSide * 0.5, containerSide * 0.5};
    
    tUp = [self minorEquilateralTriangleWithCenter:cUp];
    tLeft = [self minorEquilateralTriangleWithCenter:cLeft];
    tRight = [self minorEquilateralTriangleWithCenter:cRight];
    tCenter = [self minorEquilateralTriangleWithCenter:cCenter];
    tCenter.transform = CGAffineTransformMakeRotation(D2R(180));

    minors = [NSArray arrayWithObjects:tUp,tLeft,tRight,tCenter, nil];
    
    [minors enumerateObjectsUsingBlock:^(UIView* v, NSUInteger idx, BOOL *stop)
    {
        [self addSubview:v];
    }];
    
    return infiniteTriangle;
}


#pragma mark -

-(void)start
{
    [self rotate];
    [self scale];
    [self moveOut];
}


-(void)reset
{
    [self.layer removeAllAnimations];
    self.transform = CGAffineTransformIdentity;
    
    [minors enumerateObjectsUsingBlock:^(UIView* v, NSUInteger idx, BOOL *stop)
    {
        if(v != tCenter)
        {
            [v.layer removeAllAnimations];
            v.alpha = 1;
            v.transform = CGAffineTransformIdentity;
        }
    }];
}


#pragma mark -

-(void)rotate
{
    [UIView animateWithDuration:DURA * 0.5 delay:0 options:UIViewAnimationOptionCurveLinear animations:^
    {
        self.transform = CGAffineTransformRotate(self.transform, D2R(150));
    }completion:nil];
    
    
    [UIView animateWithDuration:DURA * 0.5 delay:DURA * 0.5 options:UIViewAnimationOptionCurveLinear animations:^
    {
        self.transform = CGAffineTransformRotate(self.transform, D2R(150));
    }
    completion:^(BOOL finished)
    {
        [self reset];
        [self start];
    }];
}


-(void)scale
{
    [UIView animateWithDuration:DURA delay:0 options:UIViewAnimationOptionCurveLinear animations:^
    {
        self.transform = CGAffineTransformScale(self.transform, SCALE, SCALE);
    }completion:nil];
}


-(void)moveOut
{
    float moveOutDistance = _side * 0.2;
    
    [UIView animateWithDuration:DURA / 3.0 delay:DURA * 0.0 / 3.0 options:0 animations:^
    {
        tUp.transform = CGAffineTransformScale(CGAffineTransformMakeTranslation(0, -moveOutDistance), SHRINK, SHRINK);
        tUp.alpha = 0;
    }completion:nil];
    
    [UIView animateWithDuration:DURA / 3.0 delay:DURA * 1.0 / 3.0 options:0 animations:^
    {
        tRight.transform = CGAffineTransformScale(CGAffineTransformMakeTranslation(0.65 * moveOutDistance * sqrt(3), 0.65 * moveOutDistance), SHRINK, SHRINK);
        tRight.alpha = 0;
    }completion:nil];
    
    [UIView animateWithDuration:DURA / 3.0 delay:DURA * 2.0 / 3.0 options:0 animations:^
    {
        tLeft.transform = CGAffineTransformScale(CGAffineTransformMakeTranslation(-0.78 * moveOutDistance * sqrt(3), 0.78 * moveOutDistance), SHRINK, SHRINK);
        tLeft.alpha = 0;
    }completion:nil];
}


#pragma mark -

-(UIView*)minorEquilateralTriangleWithCenter:(CGPoint)center
{
    CGFloat minorSide = _side * 0.5;
    CGFloat minorContainerSide = _side * 0.5 * (sqrt(3) * 2.0 / 3.0);
    
    UIView* minorTriangleView = [UIView.alloc initWithFrame:(CGRect){center.x - minorContainerSide * 0.5 , center.y - minorContainerSide * 0.5, minorContainerSide, minorContainerSide}];
    
    CGPoint top = (CGPoint){minorContainerSide * 0.5, 0.0};
    CGPoint left = (CGPoint){(minorContainerSide - minorSide) * 0.5, minorSide * 0.5 * sqrt(3)};
    CGPoint right = left;
    right.x += minorSide;
    
    UIBezierPath* trianglePath = [UIBezierPath bezierPath];
    [trianglePath moveToPoint:top];
    [trianglePath addLineToPoint:left];
    [trianglePath addLineToPoint:right];
    [trianglePath closePath];
    
    CAShapeLayer* triangleLayer = CAShapeLayer.layer;
    triangleLayer.path = trianglePath.CGPath;
    triangleLayer.lineWidth = 0.33;
    triangleLayer.strokeColor = UIColor.blackColor.CGColor;
    triangleLayer.lineCap = @"round";
    triangleLayer.fillColor = UIColor.blackColor.CGColor;
    [minorTriangleView.layer addSublayer:triangleLayer];
    
    return minorTriangleView;
}


-(void) setBackgroundColor:(UIColor *)backgroundColor
{
    [super setBackgroundColor:UIColor.clearColor];
    
    [minors enumerateObjectsUsingBlock:^(UIView* v, NSUInteger idx, BOOL *stop)
    {
        ((CAShapeLayer*)v.layer.sublayers.firstObject).fillColor = backgroundColor.CGColor;
        ((CAShapeLayer*)v.layer.sublayers.firstObject).strokeColor = backgroundColor.CGColor;
    }];
}

@end

https://dribbble.com/shots/2546822-Equilateral-Triangle-Infinite-Animation