首先说下 3 个imageView的轮播，这个逻辑分析起来 比较简单，
先上传个图片吧：：：：：
主要分析起来，核心就是这样 ：新的图片永远是加在中间ImageView上的，下一轮的第一张图片，是上一轮的第二张图片，这样就可以形成一个无缝滚动了，
只是切换了数据的逻辑。难理解就算了，看代码才容易懂………………
.h 的声明文件
@interface ImageViewShuffling : UIView @property (nonatomic,strong)NSArray *array; @end
.m 的具体实现，这里是理解这个逻辑的好地方————————
@interface ImageViewShuffling ()<UIScrollViewDelegate> @property (nonatomic,strong)UIScrollView *scrollView; @property (nonatomic,strong)UIImageView *leftImageView;
@property (nonatomic,strong)UIImageView *centerImageView;
@property (nonatomic,strong)UIImageView *rightImageView; @property (nonatomic,assign)NSInteger currentIndex; @end @implementation ImageViewShuffling
@synthesize array = _array; -(instancetype)initWithFrame:(CGRect)frame{ if (self == [super initWithFrame:frame]) {
self.currentIndex = ;
}
return self;
} -(UIScrollView*)scrollView{ if (_scrollView == nil) {
CGRect scrollRect = CGRectMake(, , self.frame.size.width, self.frame.size.height);
_scrollView = [[UIScrollView alloc]initWithFrame:scrollRect];
[self addSubview:_scrollView];
_scrollView.pagingEnabled = YES;
_scrollView.delegate = self;
}
return _scrollView;
} -(void)setArray:(NSArray *)array{ NSAssert(array.count != , @"传入的滚动数组是 空的");
_array = array;
[self initImageViews];
} -(void)initImageViews{ self.leftImageView = [[UIImageView alloc]initWithFrame:CGRectMake(, , self.frame.size.width, self.frame.size.height)];
self.centerImageView = [[UIImageView alloc]initWithFrame:CGRectMake(self.frame.size.width, , self.frame.size.width, self.frame.size.height)];
self.rightImageView = [[UIImageView alloc]initWithFrame:CGRectMake(self.frame.size.width*, , self.frame.size.width, self.frame.size.height)];
self.leftImageView.contentMode = UIViewContentModeScaleAspectFit;
self.centerImageView.contentMode = UIViewContentModeScaleAspectFit;
self.rightImageView.contentMode = UIViewContentModeScaleAspectFit; [self.scrollView addSubview:self.leftImageView];
[self.scrollView addSubview:self.centerImageView];
[self.scrollView addSubview:self.rightImageView];
/*
千万不要忘记设置这里
*/
self.scrollView.contentSize = CGSizeMake(self.frame.size.width * , );
self.scrollView.contentOffset = CGPointMake(self.frame.size.width , ); [self setImageWith:self.currentIndex];
} -(void)setImageWith:(NSInteger)integer{ self.centerImageView.backgroundColor = (UIColor*)self.array[integer];
self.leftImageView.backgroundColor = (UIColor*)self.array[(integer - + self.array.count)%(self.array.count)];
self.rightImageView.backgroundColor = (UIColor*)self.array[(integer + )%(self.array.count)];
}
/**
理解此处，你就能理解整个逻辑实现
*/
-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{ if (scrollView == self.scrollView) { if (scrollView.contentOffset.x > self.frame.size.width ) {//右滑 self.currentIndex = (self.currentIndex+) % (self.array.count); }else if(scrollView.contentOffset.x < self.frame.size.width ){//左滑 self.currentIndex = (self.currentIndex - + self.array.count)%(self.array.count); }else{// }
[self setImageWith:self.currentIndex];
self.scrollView.contentOffset = CGPointMake(self.frame.size.width , );
}
}
上面就是 3张图实现的 轮播图，童叟无欺………………
调用：：：：
-(void)prepareImageViewShuffling{
ImageViewShuffling *imageViewShuffling = [[ImageViewShuffling alloc]initWithFrame:CGRectMake(, , self.view.frame.size.width -, )];
[self.view addSubview:imageViewShuffling];;
imageViewShuffling.array = self.arr;
}********************************************************************************
弄懂了上面这个，相信下面介绍这个两张图片实现的轮播 ，对你就是小case
他就是对上面3张图片的简化…………
看完上面的逻辑，理解后发现, 左侧，或者右侧的 imageView 始终有一个是备用的，就像实现的代码一样，你不是向左就是向右滑动；
根据这个理由，就想到了这个，实时检测scroll 的滚动方向，这样就可以实现：一个主要显示的imageView，和一个 待显示的imageView……
越说越啰嗦，直接撸代码……
.h 文件
@interface ImageView2Shuffling : UIView
@property (nonatomic,strong)NSArray *array; @end
.m 实现文件，逻辑变化不大
@interface ImageView2Shuffling ()<UIScrollViewDelegate> @property (nonatomic,strong)UIScrollView *scrollView;
@property (nonatomic,strong)UIImageView *currentImageView;
@property (nonatomic,strong)UIImageView *otherImageView;
@property (nonatomic,assign)NSInteger currentIndex;
/*
这个是检测滚动方向的
*/
@property (nonatomic,strong)NSString *directionString;
@end @implementation ImageView2Shuffling
@synthesize array = _array; -(instancetype)initWithFrame:(CGRect)frame{ if (self == [super initWithFrame:frame]) {
self.currentIndex = ;
self.directionString = [[NSString alloc]init];
}
return self;
} -(UIScrollView*)scrollView{ if (_scrollView == nil) {
CGRect scrollRect = CGRectMake(, , self.frame.size.width, self.frame.size.height);
_scrollView = [[UIScrollView alloc]initWithFrame:scrollRect];
[self addSubview:_scrollView];
_scrollView.pagingEnabled = YES;
_scrollView.delegate = self;
}
return _scrollView;
} -(void)setArray:(NSArray *)array{ NSAssert(array.count != , @"传入的滚动数组是 空的");
_array = array;
[self initImageViews];
} -(void)initImageViews{
/*
这里写个空 frame 的imageview
*/
self.otherImageView = [[UIImageView alloc]init];
[self.scrollView addSubview:self.otherImageView]; self.currentImageView = [[UIImageView alloc]initWithFrame:CGRectMake(self.frame.size.width, , self.frame.size.width, self.frame.size.height)];
self.currentImageView.contentMode = UIViewContentModeScaleAspectFit;
[self.scrollView addSubview:self.currentImageView]; self.scrollView.contentSize = CGSizeMake(self.frame.size.width * , );
self.scrollView.contentOffset = CGPointMake(self.frame.size.width , ); [self setImageWith:self.currentIndex];
} -(void)setImageWith:(NSInteger)integer{ self.currentImageView.backgroundColor = (UIColor*)self.array[integer];
} -(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{ if (scrollView == self.scrollView) { self.directionString = @""; if (scrollView.contentOffset.x > self.frame.size.width ) {//右滑 self.currentIndex = (self.currentIndex+) % (self.array.count); }else if(scrollView.contentOffset.x < self.frame.size.width ){//左滑 self.currentIndex = (self.currentIndex - + self.array.count)%(self.array.count);
}else{//
}
[self setImageWith:self.currentIndex];
self.scrollView.contentOffset = CGPointMake(self.frame.size.width , );
}
} /*
这里集中了些 修改的代码
检测滚动方向，改变otherImageview 的位置，和颜色
*/
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{ if (scrollView == self.scrollView) { if (scrollView.contentOffset.x > self.frame.size.width ) {//右滑 [self refreshOtherImageViewWithDirectionString:@"right"];
}else if(scrollView.contentOffset.x < self.frame.size.width ){//左滑 [self refreshOtherImageViewWithDirectionString:@"left"];
}else{//
}
}
} -(void)refreshOtherImageViewWithDirectionString:(NSString*)direction{ if ([self.directionString isEqualToString:direction]) {
return ;
}
self.directionString = direction; CGRect frame; NSInteger integer;
if ([direction isEqualToString:@"right"]) { integer = (self.currentIndex+) % (self.array.count);
frame = CGRectMake(self.frame.size.width*, , self.frame.size.width, self.frame.size.height);
}else{ //if "left" integer = (self.currentIndex - + self.array.count)%(self.array.count);
frame = CGRectMake(, , self.frame.size.width, self.frame.size.height);
}
self.otherImageView.backgroundColor = (UIColor*)self.array[integer];
self.otherImageView.frame = frame;
}
写到这里，应该可以了，简单来讲，就是用一个direction 替换了一个imageview ，应该算减少了UI 的开销，增加了逻辑判断和运算
调用：：：：
-(void)prepareImageView2Shuffling{
ImageView2Shuffling *imageView2Shuffling = [[ImageView2Shuffling alloc]initWithFrame:CGRectMake(, , self.view.frame.size.width -, )];
[self.view addSubview:imageView2Shuffling];;
imageView2Shuffling.array = self.arr;
}突然感觉要超额完成任务的节拍，为自己加油点赞………………