自定義UIPageControl類 實現分頁自定義按鈕

所謂重寫UIPageControl類自定義分頁控件，其實就是通過重寫這個類的函數來更換點按鈕的圖片顯示。以下即爲繼承UIPageControl類的子類，主要是要分別設置正常與高亮狀態的圖片。

// CustomPageControl.h
#import <UIKit/UIKit.h>

@interface CustomPageControl : UIPageControl
{
     // 表示正常與高亮狀態的圖片
     UIImage *imagePageStateNormal;
     UIImage *imagePageStateHighlighted;
}
@property (nonatomic, retain) UIImage *imagePageStateNormal;
@property (nonatomic, retain) UIImage *imagePageStateHighlighted;

- (id)initWithFrame:(CGRect)frame;
@end

// CustomPageControl.m
#import "CustomPageControl.h"

@interface CustomPageControl (private)  //聲明一個私有方法，該方法不允許對象直接使用
- (void)updateDots;
@end

@implementation CustomPageControl
@synthesize imagePageStateNormal;
@synthesize imagePageStateHighlighted;

- (id)initWithFrame:(CGRect)frame
{
     self = [super initWithFrame:frame];
     return self;
}

// 設置正常狀態點按鈕的圖片
- (void)setImagePageStateNormal : (UIImage *)image
{
     [imagePageStateHighlighted release];
     imagePageStateHighlighted = [image retain];
     [self updateDots];
}

// 設置高亮狀態點按鈕的圖片
- (void)setImagePageStateHighlighed : (UIImage *)image
{
     [imagePageStateNormal release];
     imagePageStateNormal = [image retain];
     [self updateDots];
}

// 捕捉點擊事件
- (void)endTrackingWithTouch : (UITouch *)touch withEvent:(UIEvent *)event
{
     [super endTrackingWithTouch:touch withEvent:event];
     [self updateDots];
}

// 更新顯示所有的點按鈕
- (void)updateDots
{
    if(imagePageStateNormal || imagePageStateHighlighted)
    {
         NSArray *subview = self.subviews;  // 獲取所有子視圖
         for(NSInteger i =0; i<[subview count]; i++)
         {
              UIImageView *dot = [subview objectAtIndex:i];
              dot.image = self.currentPage == i ? imagePageStateNormal : imagePageStateHighlighted;
         }
    }
}

- (void)dealloc
{
     [imagePageStateNormal release], imagePageStateNormal = nil;
     [imagePageStateHighlighted release], imagePageStateHighlighted = nil;
     [super dealloc];
}
@end

現在就可以用自定義的UIPageControl類來創建和初始化分頁控件

CustomPageControl *myPageControl = [[CustomPageControl alloc] initWithFrame:CGRectMake(0,0,200,30)];
myPageControl.backgroundColor = [UIColor clearColor];
myPageControl.numberOfPages = 5;
myPageControl.currentPage = 0;
[myPageControl setImagePageStateNormal:[UIImage imageNamed:@"normal.png"]];
[myPageControl setImagePageStateHighlighted:[UIImage imageNamed:@"highlighted.png"]];
[self.view addSubview:myPageControl];
[myPageControl release];