SJPageControl
/// default is gray.
@property (nonatomic, strong) UIColor *pageIndicatorTintColor;
/// default is white.
@property (nonatomic, strong) UIColor *currentPageIndicatorTintColor;
/// default is nil.
@property (nonatomic, strong, nullable) UIImage *pageIndicatorImage;
/// default is nil.
@property (nonatomic, strong, nullable) UIImage *currentPageIndicatorImage;
/// default is [5, 5]
@property (nonatomic) CGSize pageIndicatorSize;
/// default use pageIndicatorSize.
@property (nonatomic) CGSize currenPageIndicatorSize;