由于工程里需求要用到pageControl自定义图片，用KVC设置图片会有问题，间距会变的特别大，以下是我自己的一些想法

//
//  SACustomPageControl.h
//  xxx
//
//  Created by xxx on 17/2/9.
//  Copyright © 2017年 xxxx科技有限公司. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface SACustomPageControl : UIPageControl

/**
 *  如果直接使用init初始化、可以手动定义以下属性
 *  其中pageSize为空则跟随图片size
 */
/*! 高亮图片 */
@property (nonatomic, strong) UIImage * currentImage;

/*! 默认图片 */
@property (nonatomic, strong) UIImage * defaultImage;

/*! 图标大小 */
@property (nonatomic, assign) CGSize pageSize;

/**
 创建方法

 @param frame 展示的范围大小frame
 @param currentImage 当前的点显示的图片
 @param defaultImage 默认的点显示的图片
 @param pageSize 点的大小
 @return self
 */
-(instancetype)initWithFrame:(CGRect)frame
                currentImage:(UIImage *)currentImage
             andDefaultImage:(UIImage *)defaultImage
                    pageSize:(CGSize)pageSize;

@end

//
//  SACustomPageControl.m
//  xx
//
//  Created by xxx on 17/2/9.
//  Copyright © 2017年 xxxx科技有限公司. All rights reserved.
//

#import "SACustomPageControl.h"
#import "SAViewHeader.h"

@interface SACustomPageControl()

@property (nonatomic) CGSize size;

@end
@implementation SACustomPageControl

- (instancetype)initWithFrame:(CGRect)frame
                currentImage:(UIImage *)currentImage
             andDefaultImage:(UIImage *)defaultImage
                    pageSize:(CGSize)pageSize {
    
    self = [super initWithFrame:frame];
    self.currentImage = currentImage;
    self.defaultImage = defaultImage;
    self.pageSize = pageSize;
    return self;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        
    }
    return self;
}

- (void)setUpDots {
    if (self.currentImage && self.defaultImage) {
        self.size = self.currentImage.size;
    }else {
        self.size = CGSizeMake(7 * kSACardWidthRatio(), 7 * kSACardHeightRatio());
    }
    
    if (self.pageSize.height && self.pageSize.width) {
        self.size =self.pageSize;
    }
    kSAWeakSelf(weakSelf);
    [self.subviews enumerateObjectsUsingBlock:^(__kindof UIView * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        [obj setFrame:CGRectMake(obj.frame.origin.x, obj.frame.origin.y, self.size.width, self.size.width)];
        if ([obj.subviews count] == 0) {
            UIImageView * view = [[UIImageView alloc]initWithFrame:obj.bounds];
            [obj addSubview:view];
        };
        UIImageView * view = obj.subviews[0];
        
        if (idx == weakSelf.currentPage) {
            if (weakSelf.currentImage) {
                view.image = weakSelf.currentImage;
                obj.backgroundColor = [UIColor clearColor];
            }else {
                view.image = nil;
                obj.backgroundColor = weakSelf.currentPageIndicatorTintColor;
            }
        }else if (weakSelf.defaultImage) {
            view.image = weakSelf.defaultImage;
            obj.backgroundColor = [UIColor clearColor];
        }else {
            view.image = nil;
            obj.backgroundColor = weakSelf.pageIndicatorTintColor;
        }
    }];
}


- (void)setCurrentPage:(NSInteger)page {
    [super setCurrentPage:page];
    [self setUpDots];
}

@end