级别： ★★☆☆☆
标签：「iOS」「卡片式控件」「QiCardView」
作者： MrLiuQ
审校： QiShare团队
前言：因项目中需求，需要做一个卡片式控件。故QiCardView诞生了。
首先，先来看一下QiCardView的效果图：
从命名来看，QiCardView，顾名思义，是一个可定制的卡片式UI控件。
从设计来看，QiCardView仿照UITableView的设计，支持cell复用，节省了资源。
话不多说，先来看下整体架构~
一、QiCardView整体架构设计
架构层面仿照了UITableView的设计，采用了cell复用策略。
在此基础上，融入了一些手势操作，更加富有交互性。
上架构图：
两个主类分别为QiCardView与QiCardViewCell。（仿照UITableView+UITableViewCell的设计）
-
QiCardView下有两个代理：QiCardViewDataSource、QiCardViewDelegate。（与UITableView的代理方法类似） -
QiCardViewCell下有一个代理：QiCardViewCellDelegate。（这个代理可以不关心，主要目的是辅助QiCardView里的一些处理逻辑）
二、如何自定义使用QiCardView？
Cell自定义很简单，只要新建一个类（例如：QiCardViewItemCell）继承自QiCardViewCell即可。
在Controller中，基本使用上几乎与UITableView类似。
- 初始化
CardView方法：
在上Demo之前，先介绍几个可以自定义的配置属性：
| 属性 | 类型 | 介绍 |
|---|---|---|
| visibleCount | NSInteger | 卡片Cell可见数量(默认3)。因为有复用策略，所以即实际创建的Cell数量。 |
| lineSpacing | CGFloat | 行间距(默认10.0，可自行计算scale比例来做间距) |
| interitemSpacing | CGFloat | 列间距(默认10.0，可自行计算scale比例来做间距) |
| maxAngle | CGFloat | 侧滑最大角度(默认15°)。值约小越容易划出，越大约不好划出。 |
| maxRemoveDistance | CGFloat | 最大移除距离(默认屏幕的1/4)，滑动距离不够时归位。 |
| isAlpha | CGFloat | cell是否需要渐变透明度。（默认YES） |
- (void)initViews {
_cardView = [[QiCardView alloc] initWithFrame:CGRectMake(25.0, 150.0, self.view.frame.size.width - 50.0, 420.0)];
_cardView.backgroundColor = [UIColor lightGrayColor];//!< 为了指出carddView的区域，指明背景色
_cardView.dataSource = self;
_cardView.delegate = self;
_cardView.visibleCount = 4;
_cardView.lineSpacing = 15.0;
_cardView.interitemSpacing = 10.0;
_cardView.maxAngle = 10.0;
_cardView.isAlpha = YES;
_cardView.maxRemoveDistance = 100.0;
_cardView.layer.cornerRadius = 10.0;
[_cardView registerClass:[QiCardItemCell class] forCellReuseIdentifier:qiCardCellId];
[self.view addSubview:_cardView];
}
- 数据源：
QiCardViewDataSource：
首先controller要遵守协议：<QiCardViewDataSource>
#pragma mark - QiCardViewDataSource
- (QiCardItemCell *)cardView:(QiCardView *)cardView cellForRowAtIndex:(NSInteger)index {
QiCardItemCell *cell = [cardView dequeueReusableCellWithIdentifier:qiCardCellId];
cell.cellData = _cellItems[index];
//...
return cell;
}
- (NSInteger)numberOfCountInCardView:(UITableView *)cardView {
return _cellItems.count;
}
- 代理：
QiCardViewDelegate：
还是首先controller需要遵守协议：<QiCardViewDelegate>。
#pragma mark - QiCardViewDelegate
- (void)cardView:(QiCardView *)cardView didRemoveLastCell:(QiCardViewCell *)cell forRowAtIndex:(NSInteger)index {
[cardView reloadDataAnimated:YES];
}
- (void)cardView:(QiCardView *)cardView didRemoveCell:(QiCardViewCell *)cell forRowAtIndex:(NSInteger)index {
NSLog(@"didRemoveCell forRowAtIndex = %ld", index);
}
- (void)cardView:(QiCardView *)cardView didDisplayCell:(QiCardViewCell *)cell forRowAtIndex:(NSInteger)index {
NSLog(@"didDisplayCell forRowAtIndex = %ld", index);
}
- (void)cardView:(QiCardView *)cardView didMoveCell:(QiCardViewCell *)cell forMovePoint:(CGPoint)point {
NSLog(@"move point = %@", NSStringFromCGPoint(point));
}
三、QiCardView的技术点
3.1 QiCardViewCell复用策略实现
- 注册Cell：
两种方式：registerNib、registerClass。 很简单。
/** 注册cell方法一：Nib */
- (void)registerNib:(nullable UINib *)nib forCellReuseIdentifier:(NSString *)identifier {
self.nib = nib;
self.identifier = identifier;
}
/** 注册cell方法二：Class */
- (void)registerClass:(nullable Class)cellClass forCellReuseIdentifier:(NSString *)identifier {
self.cellClass = cellClass;
self.identifier = identifier;
}
- 获取缓存Cell策略：
先看缓存池中是否有相同ID（identifier）的Cell，有的话，直接返回Cell。
若缓存池中没有，那么就new一个新的Cell啦~
/** 获取缓存cell */
- (__kindof QiCardViewCell *)dequeueReusableCellWithIdentifier:(NSString *)identifier {
for (QiCardViewCell *cell in self.reusableCells) {
if ([cell.reuseIdentifier isEqualToString:identifier]) {
[self.reusableCells removeObject:cell];
return cell;
}
}
if (self.nib) {
QiCardViewCell *cell = [[self.nib instantiateWithOwner:nil options:nil] lastObject];
cell.reuseIdentifier = identifier;
return cell;
} else if (self.cellClass) { // 注册class
QiCardViewCell *cell = [[self.cellClass alloc] initWithReuseIdentifier:identifier];
cell.reuseIdentifier = identifier;
return cell;
}
return nil;
}
- 当cell走
DidRemoveFromSuperView方法时，把cell加入缓存池。
- (void)cardViewCellDidRemoveFromSuperView:(QiCardViewCell *)cell {
//...
[self.reusableCells addObject:cell];
//...
}
3.2 cell重叠透明度渐变的实现
- 首先声明了一个静态变量：
moveCount来记录翻卡次数。（以便将cell的index与卡片的index逻辑关联）
static int moveCount = 0;//!< 记录翻页次数
- 逻辑：每个CardCell 在 “remove from super view” 的时候 moveCount+1。
#pragma mark - QiCardViewCellDelagate
- (void)cardViewCellDidRemoveFromSuperView:(QiCardViewCell *)cell {
moveCount++;
//....
}
- 逻辑：在reload方法中，需要将moveCount置
0。（很好理解，reload时，moveCount需要重新开始计算）
- (void)reloadDataAnimated:(BOOL)animated {
moveCount = 0;//!< 渐变需要
//...
}
- 关键逻辑：在每次更新布局时，设置每个Cell的渐变值（即
alpha）
/** 更新布局（动画） */
- (void)updateLayoutVisibleCellsWithAnimated:(BOOL)animated {
//...
if (_isAlpha) {
BOOL isTopCell = (i == _currentIndex - moveCount);
if (isTopCell) {//!< 如果是最上面的Cell就透明度为1
cell.alpha = 1.0;
} else {
cell.alpha = (i + 1.9) * 1.0/self.visibleCells.count;
}
}
//...
}
3.3 手势操作实现
这部分主要是手势+动画。
细节比较多，小而杂。
详细逻辑，请见源码。
#define Qi_SNAPSHOTVIEW_TAG 999
#define Qi_DEGREES_TO_RADIANS(angle) (angle / 180.0 * M_PI)
- (void)panGestureRecognizer:(UIPanGestureRecognizer*)pan {
switch (pan.state) {
case UIGestureRecognizerStateBegan:
self.currentPoint = CGPointZero;
break;
case UIGestureRecognizerStateChanged: {
CGPoint movePoint = [pan translationInView:pan.view];
self.currentPoint = CGPointMake(self.currentPoint.x + movePoint.x , self.currentPoint.y + movePoint.y);
CGFloat moveScale = self.currentPoint.x / self.maxRemoveDistance;
if (ABS(moveScale) > 1.0) {
moveScale = (moveScale > 0) ? 1.0 : -1.0;
}
CGFloat angle = Qi_DEGREES_TO_RADIANS(self.maxAngle) * moveScale;
CGAffineTransform transRotation = CGAffineTransformMakeRotation(angle);
self.transform = CGAffineTransformTranslate(transRotation, self.currentPoint.x, self.currentPoint.y);
if (self.cell_delegate && [self.cell_delegate respondsToSelector:@selector(cardViewCellDidMoveFromSuperView:forMovePoint:)]) {
[self.cell_delegate cardViewCellDidMoveFromSuperView:self forMovePoint:self.currentPoint];
}
[pan setTranslation:CGPointZero inView:pan.view];
}
break;
case UIGestureRecognizerStateEnded:
[self didPanStateEnded];
break;
case UIGestureRecognizerStateCancelled:
case UIGestureRecognizerStateFailed:
[self restoreCellLocation];
break;
default:
break;
}
}
// 手势结束操作（不考虑上下位移）
- (void)didPanStateEnded {
// 右滑移除
if (self.currentPoint.x > self.maxRemoveDistance) {
__block UIView *snapshotView = [self snapshotViewAfterScreenUpdates:NO];
snapshotView.transform = self.transform;
[self.superview.superview addSubview:snapshotView];
[self didCellRemoveFromSuperview];
CGFloat endCenterX = [UIScreen mainScreen].bounds.size.width/2 + self.frame.size.width * 1.5;
[UIView animateWithDuration:Qi_DefaultDuration animations:^{
CGPoint center = self.center;
center.x = endCenterX;
snapshotView.center = center;
} completion:^(BOOL finished) {
[snapshotView removeFromSuperview];
}];
}
// 左滑移除
else if (self.currentPoint.x < -self.maxRemoveDistance) {
__block UIView *snapshotView = [self snapshotViewAfterScreenUpdates:NO];
snapshotView.transform = self.transform;
[self.superview.superview addSubview:snapshotView];
[self didCellRemoveFromSuperview];
CGFloat endCenterX = -([UIScreen mainScreen].bounds.size.width/2 + self.frame.size.width);
[UIView animateWithDuration:Qi_DefaultDuration animations:^{
CGPoint center = self.center;
center.x = endCenterX;
snapshotView.center = center;
} completion:^(BOOL finished) {
[snapshotView removeFromSuperview];
}];
}
// 滑动距离不够归位
else {
[self restoreCellLocation];
}
}
// 还原卡片位置
- (void)restoreCellLocation {
[UIView animateWithDuration:Qi_SpringDuration delay:0
usingSpringWithDamping:Qi_SpringWithDamping
initialSpringVelocity:Qi_SpringVelocity
options:UIViewAnimationOptionCurveEaseOut
animations:^{
self.transform = CGAffineTransformIdentity;
} completion:nil];
}
// 卡片移除处理
- (void)didCellRemoveFromSuperview {
self.transform = CGAffineTransformIdentity;
[self removeFromSuperview];
if ([self.cell_delegate respondsToSelector:@selector(cardViewCellDidRemoveFromSuperView:)]) {
[self.cell_delegate cardViewCellDidRemoveFromSuperView:self];
}
}
- (void)removeFromSuperviewSwipe:(QiCardCellSwipeDirection)direction {
switch (direction) {
case QiCardCellSwipeDirectionLeft: {
[self removeFromSuperviewLeft];
}
break;
case QiCardCellSwipeDirectionRight: {
[self removeFromSuperviewRight];
}
break;
default:
break;
}
}
// 向左边移除动画
- (void)removeFromSuperviewLeft {
__block UIView *snapshotView = [self snapshotViewAfterScreenUpdates:NO];
[self.superview.superview addSubview:snapshotView];
[self didCellRemoveFromSuperview];
CGAffineTransform transRotation = CGAffineTransformMakeRotation(-Qi_DEGREES_TO_RADIANS(self.maxAngle));
CGAffineTransform transform = CGAffineTransformTranslate(transRotation, 0, self.frame.size.height/4.0);
CGFloat endCenterX = -([UIScreen mainScreen].bounds.size.width/2 + self.frame.size.width);
[UIView animateWithDuration:Qi_DefaultDuration animations:^{
CGPoint center = self.center;
center.x = endCenterX;
snapshotView.center = center;
snapshotView.transform = transform;
} completion:^(BOOL finished) {
[snapshotView removeFromSuperview];
}];
}
// 向右边移除动画
- (void)removeFromSuperviewRight {
__block UIView *snapshotView = [self snapshotViewAfterScreenUpdates:NO];
snapshotView.frame = self.frame;
[self.superview.superview addSubview:snapshotView];
[self didCellRemoveFromSuperview];
CGAffineTransform transRotation = CGAffineTransformMakeRotation(Qi_DEGREES_TO_RADIANS(self.maxAngle));
CGAffineTransform transform = CGAffineTransformTranslate(transRotation, 0, self.frame.size.height/4.0);
CGFloat endCenterX = [UIScreen mainScreen].bounds.size.width/2 + self.frame.size.width * 1.5;
[UIView animateWithDuration:Qi_DefaultDuration animations:^{
CGPoint center = self.center;
center.x = endCenterX;
snapshotView.center = center;
snapshotView.transform = transform;
} completion:^(BOOL finished) {
[snapshotView removeFromSuperview];
}];
}
四、未来可能优化的点
- 设计层面：如果将手势操作融入QiCardView中，将QiCardViewCell变成纯粹的Cell，会不会更好。（思考中）
- 应用层面：目前只支持一个ID的Cell重用，未来渴望拓展成多个ID的Cell都可重用。（PS：因为只存了一个ID，后续考虑存数组，以及对应的Cell缓存池数组。以此猜测UITableView的内部实现。）
源码：QiCardView源码。
