UITableView调用deleteRowsAtIndexPa

场景

当使用deleteRowsAtIndexPaths删除tableView中某个section的最后一个row的时候，发生系统崩溃。

原因

1. 删除了某个section的最后一个row，但是section却没有被删除，系统就会发生UI崩溃。
2. 如果修改了数据源中的section数和row数后调用tableView的reload方法就不会发生UI崩溃。
3. 推测是，如果不使用reload来刷新tableView，就要手动去管理seciton和row。

源码

 #import "ViewController.h"

 #define RGB(R,G,B) [UIColor colorWithRed:R/255.0 green:G/255.0 blue:B/255.0 alpha:1.0]

@interface ViewController () <UITableViewDataSource, UITableViewDelegate>

@property(nonatomic, strong) NSMutableArray *data;
@property(nonatomic, strong) NSMutableArray *section1;
@property(nonatomic, strong) NSMutableArray *section2;
@property(nonatomic, strong) NSMutableArray *section3;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    [self setupViews];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


- (void)setupViews {
    UITableView *tableView = [[UITableView alloc] initWithFrame:CGRectMake(0, 64, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height - 64)];
    [self.view addSubview:tableView];
    
    tableView.sectionHeaderHeight = 20;
    tableView.rowHeight = 44;
    tableView.dataSource = self;
    tableView.delegate = self;
    
    _section1 = [NSMutableArray arrayWithObjects:@1, @2, nil];
    _section2 = [NSMutableArray arrayWithObjects:@1, @2, nil];
    _section3 = [NSMutableArray arrayWithObjects:@1, nil];
    _data = [NSMutableArray arrayWithObjects:_section1, _section2, _section3, nil];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    int count = 0;
    
    if (_section1.count) {
        count ++;
    }
    
    if (_section2.count) {
        count ++;
    }
    
    if (_section3.count) {
        count ++;
    }
    
    return count;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    NSArray *a = _data[section];
    return a.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
    }
    
    cell.backgroundColor = RGB(arc4random()%255,arc4random()%255,arc4random()%255);
    
    return cell;
}

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 20)];
    
    UILabel *label = [[UILabel alloc] initWithFrame:view.bounds];
    label.text = @"header";
    label.font = [UIFont systemFontOfSize:16];
    label.textColor = [UIColor blackColor];
    [view addSubview:label];
    
    return view;
}

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        NSMutableArray *a = _data[indexPath.section];
        [a removeObjectAtIndex:indexPath.row];
        
        // 如果这样调用会发生崩溃
//        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
        
        if (a.count == 0) { // 要根据情况直接删除section或者仅仅删除row
            [tableView deleteSections:[NSIndexSet indexSetWithIndex:indexPath.section] withRowAnimation:UITableViewRowAnimationFade];
            
        } else {
            [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
        }
    }
}


@end