1. 消除plain样式的多余的(没有数据的)cell
self.tableView.tableFooterView = [UIView new];
2. 异步加载cell的内容, 优化tableView的性能
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseID forIndexPath:indexPath];
if (!cell) {
cell = [CustomCell cell];
}
// 在此处进行数据异步加载
[self asyncLoadingCellWithHandler:^(CustomModel *result) {
dispatch_async(dispatch_get_main_queue(), ^{
cell.model = result;
});
}];
return cell;
}
3. cell的插入/删除/刷新/移动
// 需要用到的相关方法
- (void)beginUpdates;
- (void)endUpdates;
- (void)insertSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation;
- (void)deleteSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation;
- (void)reloadSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation NS_AVAILABLE_IOS(3_0);
- (void)moveSection:(NSInteger)section toSection:(NSInteger)newSection NS_AVAILABLE_IOS(5_0);
- (void)insertRowsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation;
- (void)deleteRowsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation;
- (void)reloadRowsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation NS_AVAILABLE_IOS(3_0);
- (void)moveRowAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath NS_AVAILABLE_IOS(5_0);
// 获取当前cell所在的组数
NSUInteger sectionNum = indexPath.section;
// 查看当前数据所在的组中的行数
NSUInteger rowsCount = [self.tableView numberOfRowsInSection:sectionNum];
// 刷新数据源: 增加数据/删除数据/修改数据/移动数据
...
// 开始执行UI操作
[self.tableView beginUpdates];
例:
1. 删除cell
/*
如果操作的tableView是plain样式, 在删除cell的时候需要考虑到当前组中是否只有一个cell,
如果是, 需要在执行 deleteRowsAtIndexPaths:withRowAnimation: 方法的时候同时执行 deleteSections:withRowAnimation: 否则会一直报错
*/
if (rowsCount == 1) {
NSIndexSet *indexSet = [NSIndexSet indexSetWithIndex:indexPath.section];
[self.tableView deleteSections:indexSet withRowAnimation:UITableViewRowAnimationFade];
}
[self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
2. 插入cell
...
3. 更新cell
...
4. 移动cell
...
[self.tableView endUpdates];
4. plain样式的组头标题会自动悬停, group样式的组头标题不会自动悬停
在此方法中设置组头标题内容
- (nullable NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section;
5. 自定义左滑cell, 出现编辑按钮的样式
iOS 11以前, 在自定义cell的- (void)layoutSubviews方法中自定义左滑cell后的编辑按钮样式
- (void)layoutSubviews {
[super layoutSubviews];
for (UIView *subV in self.subviews.firstObject.subviews) {
if ([subV isKindOfClass:NSClassFromString(@"_UITableViewCellActionButton")]) {
UILabel *buttonLabel = subV.subviews.firstObject;// UIButtonLabel
[buttonLabel removeFromSuperview];
// 添加文字
NSString *titleStr = buttonLabel.text;
CGSize titleSize = [titleStr boundingRectWithSize:CGSizeMake(MAXFLOAT, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{
NSFontAttributeName:[UIFont systemFontOfSize:12] } context:nil].size;
CGFloat imageWH = 18;
CGFloat topAndBottomMargin = 14;
CGFloat labelX = (CGRectGetWidth(subV.frame) - titleSize.width) * 0.5;
CGFloat labelY = CGRectGetHeight(subV.frame) - (topAndBottomMargin + titleSize.height);
CATextLayer *titleLayer = [CATextLayer layer];
titleLayer.contentsScale = 2;
titleLayer.frame = CGRectMake(labelX, labelY, titleSize.width, titleSize.height);
titleLayer.string = titleStr;
titleLayer.fontSize = 12;
titleLayer.foregroundColor = [UIColor whiteColor].CGColor;
[subV.layer addSublayer:titleLayer];
// 添加图片
CGFloat imageX = (CGRectGetWidth(subV.frame) - imageWH) * 0.5;
CGFloat imageY = topAndBottomMargin;
CGRect imageRect = CGRectMake(imageX, imageY, imageWH, imageWH);
UIImage *image = nil;
if ([titleStr isEqualToString:@"删除"]) {
image = [UIImage imageNamed:@"delete_icon"];
}
if ([titleStr isEqualToString:@"发送"]) {
image = [UIImage imageNamed:@"send_icon"];
}
CALayer *layer = [CALayer layer];
layer.frame = imageRect;
layer.contents = (id)image.CGImage;
[subV.layer addSublayer:layer];
}
}
}
iOS 11以后, 在tableView的- (void)tableView:(UITableView *)tableView willBeginEditingRowAtIndexPath:(NSIndexPath *)indexPath中自定义左滑cell后的编辑按钮样式
- (void)tableView:(UITableView *)tableView willBeginEditingRowAtIndexPath:(NSIndexPath *)indexPath {
for (UIView *subV in self.tableView.subviews) {
if ([subV isKindOfClass:NSClassFromString(@"UISwipeActionPullView")]) {
for (UIButton *actionBtn in subV.subviews) {
if ([actionBtn isKindOfClass:NSClassFromString(@"UISwipeActionStandardButton")]) {
// 添加文字
NSString *titleStr = actionBtn.titleLabel.text;
CGSize titleSize = [titleStr boundingRectWithSize:CGSizeMake(MAXFLOAT, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{
NSFontAttributeName:[UIFont systemFontOfSize:12] } context:nil].size;
UILabel *actionTitleLabel = actionBtn.titleLabel;
CGFloat topMargin = 14;
CGFloat bottomMargin = topMargin;
CGFloat imageWH = 18;
CGFloat labelX = CGRectGetMinX(actionTitleLabel.frame) + (CGRectGetWidth(actionTitleLabel.frame) - titleSize.width) * 0.5;
CGFloat labelY = bottomMargin + imageWH;
CATextLayer *titleLayer = [CATextLayer layer];
titleLayer.contentsScale = 2;
titleLayer.frame = CGRectMake(labelX, labelY, titleSize.width, titleSize.height);
titleLayer.string = titleStr;
titleLayer.fontSize = 12;
titleLayer.foregroundColor = [UIColor whiteColor].CGColor;
[actionBtn.layer addSublayer:titleLayer];
// 添加图片
CGFloat imageX = CGRectGetMinX(actionTitleLabel.frame) + (CGRectGetWidth(actionTitleLabel.frame) - imageWH) * 0.5;
CGFloat imageY = topMargin;
CGRect imageRect = CGRectMake(imageX, imageY, imageWH, imageWH);
UIImage *image = nil;
if ([titleStr isEqualToString:@"删除"]) {
image = [UIImage imageNamed:@"delete_icon"];
}
if ([titleStr isEqualToString:@"发送"]) {
image = [UIImage imageNamed:@"send_icon"];
}
CALayer *layer = [CALayer layer];
layer.frame = imageRect;
layer.contents = (id)image.CGImage;
[actionBtn.layer addSublayer:layer];
// 移除系统文字
[actionTitleLabel removeFromSuperview];
}
}
}
}
}
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