iOS开发中如何实现一个平滑的颜色过渡

- (NSArray *)getRGBDictionaryByColor:(UIColor *)originColor
{
  CGFloat r=0,g=0,b=0,a=0;
  if ([self respondsToSelector:@selector(getRed:green:blue:alpha:)]) {
    [originColor getRed:&r green:&g blue:&b alpha:&a];
  }
  else {
    const CGFloat *components = CGColorGetComponents(originColor.CGColor);
    r = components[0];
    g = components[1];
    b = components[2];
    a = components[3];
  }
  return @[@(r),@(g),@(b)];
}

- (NSArray *)transColorBeginColor:(UIColor *)beginColor andEndColor:(UIColor *)endColor {
  NSArray<NSNumber *> *beginColorArr = [self getRGBDictionaryByColor:beginColor];
//  NSArray<NSNumber *> *endColorArr = [self getRGBDictionaryByColor:endColor];
  NSArray<NSNumber *> *endColorArr = @[@(1.0),@(1.0),@(1.0)];
  return @[@([endColorArr[0] doubleValue] - [beginColorArr[0] doubleValue]),@([endColorArr[1] doubleValue] - [beginColorArr[1] doubleValue]),@([endColorArr[2] doubleValue] - [beginColorArr[2] doubleValue])];
}

- (UIColor *)getColorWithColor:(UIColor *)beginColor andCoe:(double)coe andMarginArray:(NSArray<NSNumber *> *)marginArray {
  NSArray *beginColorArr = [self getRGBDictionaryByColor:beginColor];
  double red = [beginColorArr[0] doubleValue] + coe * [marginArray[0] doubleValue];
  double green = [beginColorArr[1] doubleValue]+ coe * [marginArray[1] doubleValue];
  double blue = [beginColorArr[2] doubleValue] + coe * [marginArray[2] doubleValue];
  return RGBNUM(red, green, blue);
}