ios 关于UIPageControl 自定义样式定制的正确姿势

本文链接：https://blog.csdn.net/a416863220/article/details/43407517

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：

// 设置非选中页的圆点颜色
_pageControl.pageIndicatorTintColor = [UIColor redColor];
// 设置选中页的圆点颜色
_pageControl.currentPageIndicatorTintColor = [UIColor blueColor];

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：

image

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。

最后编辑于：2020.10.20 17:30:26