ios 關于UIPageControl 自定義樣式定制的正確姿勢

本文鏈接：https://blog.csdn.net/a416863220/article/details/43407517

近來联贩，項目中需要定制UIPageControl樣式抵赢，目前知道的方式大概如下葫辐，這里簡單概括：

一刨裆、修改顏色聂示，最簡單的方式：

// 設置非選中頁的圓點顏色
_pageControl.pageIndicatorTintColor = [UIColor redColor];
// 設置選中頁的圓點顏色
_pageControl.currentPageIndicatorTintColor = [UIColor blueColor];

二告唆、修改靜態(tài)圖標樣式棺弊，可以采用KVO方式，這種弊端是只能靜態(tài)顯示擒悬，無法動態(tài)替換模她，且私有，危險：

[_pageControl setValue:[UIImage imageNamed:@"image1"] forKeyPath:@"_pageImage"]; 
[_pageControl setValue:[UIImage imageNamed:@"image2"] forKeyPath:@"_currentPageImage"];

三懂牧、替換系統(tǒng)默認圖標侈净，自定義樣式：

常規(guī)方式便是創(chuàng)建一個類，繼承于UIPageControl僧凤，重新set方式畜侦，這里寫下核心代碼，也是目前網(wǎng)絡上的方式：

-(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;   
     
 }

結果是程序崩潰躯保，歸咎原因：

這種方式及其危險的夏伊，因為[self.subviews objectAtIndex:i] class 為UIView, 而 UIImageView *dot = [self.subviews objectAtIndex:i]; 這句是將一個UIView轉(zhuǎn)換為UIImageView, 故容易crash 掉，特此放棄如上國內(nèi)方式吻氧；

四溺忧、完善上面第三種方式，轉(zhuǎn)為安全的替換方式盯孙，核心代碼如下：

for (UIView *subview in view.subviews) {          
  if ([subview isKindOfClass:[UIImageView class]]) {           
     dot = (UIImageView *)subview;         
      break;       
     }      
  }

采用如上安全方式鲁森，可有效防止崩潰，至此完成項目需求振惰，效果如下：

image

五歌溉、這里把整個代碼放出來，幫助大家少走彎路骑晶，具體代碼如下：

1痛垛、.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桶蛔、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);     
 //去掉系統(tǒng)自帶樣式
pageCtrl.currentPageIndicatorTintColor = [UIColor clearColor];
pageCtrl.pageIndicatorTintColor = [UIColor clearColor];

至此匙头，定制UIPageControl的正確姿勢已了解，希望對大家有用仔雷。

最后編輯于：2020.10.20 17:30:26

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