转自：https://blog.csdn.net/mapboo/article/details/79813383
近来，项目中需要定制UIPageControl样式，目前知道的方式大概如下，这里简单概括：
一、修改颜色，最简单的方式：
_pageControl.pageIndicatorTintColor = [UIColor redColor];// 设置非选中页的圆点颜色
_pageControl.currentPageIndicatorTintColor = [UIColor blueColor]; // 设置选中页的圆点颜色
二、修改静态图标样式，可以采用KVO方式，这种弊端是只能静态显示，无法动态替换，且私有，危险：
[_pageControl setValue:[UIImage imageNamed:@"image1"] forKeyPath:@"_pageImage"];
[_pageControl setValue:[UIImage imageNamed:@"image2"] forKeyPath:@"_currentPageImage"];
三、替换系统默认图标，自定义样式：
常规方式便是创建一个类，继承于UIPageControl，重新set方式，这里写下核心代码，也是目前网络上的方式：
-(void) updateDots {
for (int i = 0; i < [self.subviews count]; i++) {
UIImageView *dot = [self.subviews objectAtIndex:i];
if (i == self.currentPage) dot.image = activeImage;
else dot.image = inactiveImage;
}
}
结果是程序崩溃，归咎原因：
这种方式及其危险的，因为[self.subviews objectAtIndex:i] class 为UIView, 而 UIImageView *dot = [self.subviews objectAtIndex:i]; 这句是将一个UIView转换为UIImageView, 故容易crash 掉，特此放弃如上国内方式；
四、完善上面第三种方式，转为安全的替换方式，核心代码如下：
for (UIView *subview in view.subviews) {
if ([subview isKindOfClass:[UIImageView class]]) {
dot = (UIImageView *)subview;
break;
}
}
采用如上安全方式，可有效防止崩溃，至此完成项目需求，效果如下：
五、这里把整个代码放出来，帮助大家少走弯路，具体代码如下：
1、.h文件
#import <UIKit/UIKit.h>
@interface CustomPageControl : UIPageControl
@property (nonatomic, strong) UIImage *currentImage;
@property (nonatomic, strong) UIImage *inactiveImage;
@property (nonatomic, assign) CGSize currentImageSize;
@property (nonatomic, assign) CGSize inactiveImageSize;
@end
2、.m文件
#import "CustomPageControl.h"
@implementation CustomPageControl
- (instancetype)init{
self = [super init];
if (self) {
self.userInteractionEnabled = NO;
}
return self;
}
- (void)setCurrentPage:(NSInteger)currentPage{
[super setCurrentPage:currentPage];
[self updateDots];
}
- (void)updateDots{
for (int i = 0; i < [self.subviews count]; i++) {
UIImageView *dot = [self imageViewForSubview:[self.subviews objectAtIndex:i] currPage:i];
if (i == self.currentPage){
dot.image = self.currentImage;
dot.size = self.currentImageSize;
}else{
dot.image = self.inactiveImage;
dot.size = self.inactiveImageSize;
}
}
}
- (UIImageView *)imageViewForSubview:(UIView *)view currPage:(int)currPage{
UIImageView *dot = nil;
if ([view isKindOfClass:[UIView class]]) {
for (UIView *subview in view.subviews) {
if ([subview isKindOfClass:[UIImageView class]]) {
dot = (UIImageView *)subview;
break;
}
}
if (dot == nil) {
dot = [[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, view.frame.size.width, view.frame.size.height)];
[view addSubview:dot];
}
}else {
dot = (UIImageView *)view;
}
return dot;
}
@end
3、使用方式：
CustomPageControl *pageCtrl = [[CustomPageControl alloc] initWithFrame:CGRectMake(0, 10, mScreenWidth, 5)];
pageCtrl.numberOfPages = cardSwitchViewAry.count;
pageCtrl.currentPage = 0;
pageCtrl.userInteractionEnabled = NO;
pageCtrl.inactiveImage = [UIImage imageNamed:@"ex_page_1"];
pageCtrl.inactiveImageSize = CGSizeMake(5, 5);
pageCtrl.currentImage = [UIImage imageNamed:@"ex_page_2"];
pageCtrl.currentImageSize = CGSizeMake(10, 5);
//去掉系统自带样式
pageCtrl.currentPageIndicatorTintColor = [UIColor clearColor];
pageCtrl.pageIndicatorTintColor = [UIColor clearColor];
至此，定制UIPageControl的正确姿势已了解，希望对大家有用。
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