在列表中我们经常使用下拉刷新和上提更新的功能，在网络请求数据返回之后，我们会停止刷新，但是何时停止刷新呢？在数据返回之后立刻停止刷新吗？还是在保存数据的变量赋值完成之后呢？
在我们的项目中，有一个获取优惠券数据的接口，代码如下
[Coupon myCouponListSpecificWithType:couponType andGetNum:1 pageType:self.pageTypeOption block:^(Coupon *coupon, NSInteger type, NSString *notUsedNum, NSString *usedNum, NSString *overdueNum, NSString *error, NSInteger errorCode) {
if (weakSelf) {
typeof(self) strongSelf = weakSelf;
if (strongSelf->couponType != type) {
return ;
}
UITableView *tableView = nil;
if (type == 0) {
tableView = strongSelf->usableTableView;
} else if (type == 1) {
tableView = strongSelf->unusableTableView;
} else {
tableView = strongSelf->overdueTableView;
}
if (tableView.pullToRefreshView.state == SVPullToRefreshStateLoading) {
[tableView.pullToRefreshView stopAnimating];
}
if (tableView.infiniteScrollingView.state == SVInfiniteScrollingStateLoading) {
[tableView.infiniteScrollingView stopAnimating];
}
strongSelf.isExchangeDoneFlag = NO;
if (error) {
if (errorCode != 0) {
[strongSelf showBadNetworkView];
} else {
[self hiddenViewWhenNoNetWork:NO];
[[Util defaultUtil] showAlert:error];
}
} else {
[self hiddenViewWhenNoNetWork:NO];
[strongSelf.badNetWorkView disappear];
[strongSelf removeAllBadNetwrokView];
strongSelf->isDownloadFinishData = YES;
strongSelf->couponModel = coupon;
strongSelf->notUsedCouponNumber = [notUsedNum integerValue];
strongSelf->usedCouponNumber = [usedNum integerValue];
strongSelf->overdueCouponNumber = [overdueNum integerValue];
[strongSelf updateBtnTitleWithNumber:notUsedNum andUseNum:usedNum andOverdueNum:overdueNum]; //更新页签标题
if (coupon.reduceCouponsArray.count==0 && coupon.cashCouponsArray.count==0) {
CGRect rect = strongSelf.noCouponImageView.frame;
rect.origin.x = strongSelf->couponType * strongSelf.view.frame.size.width + (strongSelf.view.frame.size.width - 79)/2;
strongSelf.noCouponImageView.frame = rect;
rect = strongSelf.noCouponLabel.frame;
rect.origin.x = couponType * strongSelf.view.frame.size.width + (strongSelf.view.frame.size.width - 200)/2;
strongSelf.noCouponLabel.frame = rect;
[strongSelf->listView addSubview:strongSelf.noCouponImageView];
[strongSelf->listView addSubview:strongSelf.noCouponLabel];
[tableView setHidden:YES];
}else {
if (strongSelf.noCouponImageView) {
[strongSelf.noCouponImageView removeFromSuperview];
[strongSelf.noCouponLabel removeFromSuperview];
}
if (strongSelf->couponID) {
strongSelf->exchangeCouponIndexPath = [strongSelf obtainExchangeCouponIndexPath];
DLog(@"indexPath:%@,couponID:%@", strongSelf->exchangeCouponIndexPath, strongSelf->couponID);
}
[tableView setHidden:NO];
}
}
//0-未使用 1-已使用 2-已过期
DLog(@"couponType:%ld", (long)type);
if (type == 0) {
[strongSelf->usableTableView reloadData];
//兑换成功后刷新，跳转至可用列表的相应位置
if (strongSelf->couponID) {
[strongSelf->usableTableView scrollToRowAtIndexPath:exchangeCouponIndexPath atScrollPosition:UITableViewScrollPositionTop animated:NO];
strongSelf->couponID = nil;
}
} else if (type == 1) {
[strongSelf->unusableTableView reloadData];
} else if (type == 2) {
[strongSelf->overdueTableView reloadData];
}
}
}];
初看代码，数据返回来之后判断数据返回的类型是否跟请求的类型一致，如果不一致则不进行任何处理，然后停止加载中的动画，数据处理，表格刷新！
问题恰恰出现在先停止加载中的动画，这个时候系统会调用
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
这个方法，那么数据源我还没有改变，还是使用之前的数据源，那么就会崩溃喽
所以正确的做法是在更新完数据源之后，在进行停止加载中的动画，代码如下：
[Coupon myCouponListSpecificWithType:couponType andGetNum:1 pageType:self.pageTypeOption block:^(Coupon *coupon, NSInteger type, NSString *notUsedNum, NSString *usedNum, NSString *overdueNum, NSString *error, NSInteger errorCode) {
if (weakSelf) {
typeof(self) strongSelf = weakSelf;
if (strongSelf->couponType != type) {
return ;
}
UITableView *tableView = nil;
if (type == 0) {
tableView = strongSelf->usableTableView;
} else if (type == 1) {
tableView = strongSelf->unusableTableView;
} else {
tableView = strongSelf->overdueTableView;
}
strongSelf.isExchangeDoneFlag = NO;
if (error) {
if (errorCode != 0) {
[strongSelf showBadNetworkView];
} else {
[self hiddenViewWhenNoNetWork:NO];
[[Util defaultUtil] showAlert:error];
}
} else {
[self hiddenViewWhenNoNetWork:NO];
[strongSelf.badNetWorkView disappear];
[strongSelf removeAllBadNetwrokView];
strongSelf->isDownloadFinishData = YES;
strongSelf->couponModel = coupon;
strongSelf->notUsedCouponNumber = [notUsedNum integerValue];
strongSelf->usedCouponNumber = [usedNum integerValue];
strongSelf->overdueCouponNumber = [overdueNum integerValue];
[strongSelf updateBtnTitleWithNumber:notUsedNum andUseNum:usedNum andOverdueNum:overdueNum]; //更新页签标题
if (coupon.reduceCouponsArray.count==0 && coupon.cashCouponsArray.count==0) {
CGRect rect = strongSelf.noCouponImageView.frame;
rect.origin.x = strongSelf->couponType * strongSelf.view.frame.size.width + (strongSelf.view.frame.size.width - 79)/2;
strongSelf.noCouponImageView.frame = rect;
rect = strongSelf.noCouponLabel.frame;
rect.origin.x = couponType * strongSelf.view.frame.size.width + (strongSelf.view.frame.size.width - 200)/2;
strongSelf.noCouponLabel.frame = rect;
[strongSelf->listView addSubview:strongSelf.noCouponImageView];
[strongSelf->listView addSubview:strongSelf.noCouponLabel];
[tableView setHidden:YES];
}else {
if (strongSelf.noCouponImageView) {
[strongSelf.noCouponImageView removeFromSuperview];
[strongSelf.noCouponLabel removeFromSuperview];
}
if (strongSelf->couponID) {
strongSelf->exchangeCouponIndexPath = [strongSelf obtainExchangeCouponIndexPath];
DLog(@"indexPath:%@,couponID:%@", strongSelf->exchangeCouponIndexPath, strongSelf->couponID);
}
[tableView setHidden:NO];
}
}
if (tableView.pullToRefreshView.state == SVPullToRefreshStateLoading) {
[tableView.pullToRefreshView stopAnimating];
}
if (tableView.infiniteScrollingView.state == SVInfiniteScrollingStateLoading) {
[tableView.infiniteScrollingView stopAnimating];
}
//0-未使用 1-已使用 2-已过期
DLog(@"couponType:%ld", (long)type);
if (type == 0) {
[strongSelf->usableTableView reloadData];
//兑换成功后刷新，跳转至可用列表的相应位置
if (strongSelf->couponID) {
[strongSelf->usableTableView scrollToRowAtIndexPath:exchangeCouponIndexPath atScrollPosition:UITableViewScrollPositionTop animated:NO];
strongSelf->couponID = nil;
}
} else if (type == 1) {
[strongSelf->unusableTableView reloadData];
} else if (type == 2) {
[strongSelf->overdueTableView reloadData];
}
}
}]
编程是一种修行，时刻要谨慎小心！