Custom activity indicator

MPActivityIndicator.h

@interface MPActivityIndicator : UIView

@property (nonatomic, readonly, getter = isAnimating) BOOL animating;

- (void)stopAnimating;
- (void)startAnimating;

- (void)rotateLoadingCircleByPercents:(CGFloat)percents;

@end

MPActivityIndicator.m

#import "MPActivityIndicator.h"

#import <QuartzCore/QuartzCore.h>

#define WIDTH 320
#define HEIGHT 480

#define kBGImageSmall [UIImage imageNamed:@"Loadingcircle.png"]
#define kBGImageBig [UIImage imageNamed:@"Refreshcircle.png"]

#define ANIMATION_DURATION 1.0f

@interface MPActivityIndicator () {
  UIImageView *__background;
  UIImageView *__loader;
  
  BOOL __animating;
  
  CGFloat __previousRotationAngle;
}

@end

@implementation MPActivityIndicator

@synthesize animating = __animating;

#pragma mark -
#pragma mark Lifecycle


- (id)init {
  
  self = [super init];  
  
  if (self) {
    self.backgroundColor = [UIColor clearColor];
    // place init code here
    
    __previousRotationAngle = 0.0;
    
    __loader = [[UIImageView alloc] initWithImage:kLoaderImageBig];
    __background = [[UIImageView alloc] initWithImage:kBGImageBig];
    
    [self addSubview:__background];
    [self addSubview:__loader];
  }  
  
  return self;
}

- (void)layoutSubviews {
  
  [super layoutSubviews];
  
  if ( !CGRectEqualToRect(__loader.frame, self.bounds) ) {
    __loader.frame = self.bounds;
  }
  
  if ( !CGRectEqualToRect(__background.frame, self.bounds) ) {
    __background.frame = self.bounds;
  }

}

#pragma mark -
#pragma mark Public

- (void)rotateLoadingCircleByPercents:(CGFloat)percents {
  
  if ( __animating ) {
    return;
  }
  
  CGFloat ratio = fabsf(percents) / 100.0;
  CGFloat radians = ratio * M_PI * 2.0;
  CGFloat newradians = radians - __previousRotationAngle;
  __previousRotationAngle = radians;
  
  CATransform3D matrix = __loader.layer.transform;
  matrix.m34 = 1.0 / -500.0;
  __loader.layer.transform = CATransform3DRotate(matrix, newradians, 0.0, 0.0, 1.0);
  
}

- (void)startAnimating {
  
  if ( __animating ) {
    return;
  }
  
  [__loader.layer removeAnimationForKey:@"rotationAnimation"];
  
  CABasicAnimation* rotationAnimation;
  rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
  rotationAnimation.fromValue = [NSNumber numberWithFloat:0.0];
  rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2.0 ];
  rotationAnimation.duration = ANIMATION_DURATION;
  rotationAnimation.additive = YES;
  rotationAnimation.repeatCount = HUGE_VALF;
  
  [__loader.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
  
  __animating = YES;
}

- (void)stopAnimating {
  
  [__loader.layer removeAnimationForKey:@"rotationAnimation"];
  __loader.layer.transform = CATransform3DIdentity;
  
  __animating = NO;
}

#pragma mark -
#pragma mark Memory management

- (void)dealloc {

  TW_RELEASE( __loader );
  TW_RELEASE( __background );
  
  [super dealloc];
}

@end