我在UITableViewController中有一个UISearchController。我想在每次显示表格视图时使用最后搜索的文本填充搜索栏。为此，我在viewDidAppear中添加了代码以检索最后一个搜索字符串并将UISearchController设置为活动状态。
每当我不输入任何搜索文本时，一切正常。
输入搜索文本后，搜索第一次正常。但是，当我重新打开此视图，并使用最后一个搜索项填充UISearchController时，如果新列表现在返回空结果（可能因为我在tableview中的列表是动态的），那么应用程序崩溃了cellForRowAtIndexPath，尝试将行访问到空搜索结果数组中。
我把NSLogs放在很多地方，发现了一件奇怪的事情。即使UISearchController处于活动状态，numberOfRowsInSection中的相应条件也会返回FALSE，从而返回原始项目列表中的项目数，而不是搜索项目列表（现在为0）。
当搜索控制器处于活动状态时，它调用numOfRowsInSection，而不是进入＆＃34; if（[_searchController isActive]）＆＃34;该功能的子句，不正确进入＆＃34;否则＆＃34;条款，获取原始列表＆＃39; count（非搜索），为0，然后使用indexPath.row = 0调用cellForRowAtIndexPath。奇怪的是，在cellForRowAtIndexPath中，它确实正确在＆＃34; if（_searchController.active）＆ ＃34;条款。显然存在一些竞争条件，或者我遗漏了一些东西。
我很困惑为什么会这样。非常感谢任何帮助。
@interface TaalListViewController ()
@property (strong, nonatomic) NSArray *m_searchedItemList;
@property NSArray *m_itemList;
@property (retain, nonatomic) UISearchController *searchController;
@end
@implementation TaalListViewController
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
@try {
[super viewDidLoad];
// Uncomment the following line to preserve selection between presentations.
// self.clearsSelectionOnViewWillAppear = NO;
// This is a global function declared and returns the items list. This works fine.
_m_itemList = [Globals getItemsList];
// Search controller
_m_searchedItemList = [_m_itemList mutableCopy];
self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
self.searchController.searchBar.delegate = self;
self.searchController.searchResultsUpdater = self;
[self.searchController.searchBar sizeToFit];
self.searchController.dimsBackgroundDuringPresentation = NO;
self.definesPresentationContext = YES;
self.tableView.tableHeaderView = self.searchController.searchBar;
}
@catch (NSException *exception) {
NSLog(@"Caught exception in viewDidLoad");
NSLog(@"CRASH: %@", exception);
NSLog(@"Stack Trace: %@", [exception callStackSymbols]);
}
}
- (void) viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
// Get the last searched text and automatically set it in the search bar
NSString *str = [Globals getLastSearchedText];
if ((str != nil) && (!(str.length == 0)))
{
NSLog(@"Setting seach bar active automatically");
self.searchController.searchBar.text = str;
self.searchController.active = YES;
// [self.searchController.searchBar becomeFirstResponder];
}
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
@try {
// Return the number of rows in the section.
if ([self.searchController isActive])
{
NSLog(@"Number of searched item rows = %lu", (unsigned long)_m_searchedItemList.count);
return _m_searchedItemList.count;
}
else
{
NSLog(@"Number of regular rows = %lu", (unsigned long)_m_itemList.count);
return _m_itemList.count;
}
}
@catch (NSException *exception) {
NSLog(@"Caught exception in numberOfRowsInSection");
NSLog(@"CRASH: %@", exception);
NSLog(@"Stack Trace: %@", [exception callStackSymbols]);
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
@try {
static NSString *CellIdentifier = @"ListTableCell";
ListTableViewCell *cell = (ListTableViewCell *) [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Configure the cell...
if (cell == nil)
{
cell = [[ListTableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
DisplayListItem *item = nil;
if (self.searchController.active)
{
NSLog(@"Row %ld of search list", (long)indexPath.row);
item = (DisplayListItem *) [_m_searchedItemList objectAtIndex:indexPath.row];
}
else
{
NSLog(@"Row %ld of regular list", (long)indexPath.row);
item = (DisplayListItem *) [_m_itemList objectAtIndex:indexPath.row];
}
// Set the cell here and return
// ...
// Omitted code
// ...
return cell;
}
@catch (NSException *exception) {
NSLog(@"Caught exception in cellForRowAtIndexPath");
NSLog(@"CRASH: %@", exception);
NSLog(@"Stack Trace: %@", [exception callStackSymbols]);
}
}
#pragma mark - UISearchResultsUpdating
-(void)updateSearchResultsForSearchController:(UISearchController *)searchController {
NSString *searchString = [self.searchController.searchBar text];
NSLog(@"updateSearchResultsForSearchController called, searchString = %@", searchString);
_m_searchedItemList = [_m_itemList mutableCopy];
if (searchString.length != 0)
{
[self filterContentForSearchText:searchString];
}
[self.tableView reloadData];
}
#pragma mark - UISearchBarDelegate
- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar {
NSLog(@"searchBarSearchButtonClicked called");
[searchBar resignFirstResponder];
}
- (void)filterContentForSearchText:(NSString*)searchText
{
NSLog(@"filterContentForSearchText called");
@try {
NSMutableArray *subPredicates = [NSMutableArray arrayWithCapacity:searchText.count];
for (NSString *searchStr in searchText)
{
[subPredicates addObject:[NSPredicate predicateWithFormat:@"m_name contains[c] %@", searchStr]];
}
NSPredicate *resultPredicate = [NSCompoundPredicate orPredicateWithSubpredicates:subPredicates];
_m_searchedItemList = [_m_itemList filteredArrayUsingPredicate:resultPredicate];
[Globals setLastSearchedText:searchText];
NSLog(@"filterContentForSearchText finished, searched count = %lu", _m_searchedItemList.count);
}
@catch (NSException *exception) {
NSLog(@"Caught exception in filterContentForSearchText");
NSLog(@"CRASH: %@", exception);
NSLog(@"Stack Trace: %@", [exception callStackSymbols]);
}
}
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
[Globals setLastSearchedText:searchText];
}
@end
以下是调试器中NSLog的输出。
2016-10-04 22:45:46.364927 AppName[1387:639346] Setting seach bar active automatically
2016-10-04 22:45:46.365378 AppName[1387:639346] updateSearchResultsForSearchController called, searchString = Kay
2016-10-04 22:45:46.365470 AppName[1387:639346] filterContentForSearchText called
2016-10-04 22:45:46.366522 AppName[1387:639346] filterContentForSearchText finished, searched count = 0
2016-10-04 22:45:46.366825 AppName[1387:639346] Number of regular rows = 215
2016-10-04 22:45:46.367319 AppName[1387:639346] updateSearchResultsForSearchController called, searchString = Kay
2016-10-04 22:45:46.367407 AppName[1387:639346] filterContentForSearchText called
2016-10-04 22:45:46.368190 AppName[1387:639346] filterContentForSearchText finished, searched count = 0
2016-10-04 22:45:46.368264 AppName[1387:639346] Number of regular rows = 215
2016-10-04 22:45:46.371081 AppName[1387:639346] Row 0 of search list
2016-10-04 22:45:46.373274 AppName[1387:639346] Caught exception in cellForRowAtIndexPath
2016-10-04 22:45:46.373383 AppName[1387:639346] CRASH: *** -[__NSArray0 objectAtIndex:]: index 0 beyond bounds for empty NSArray
2016-10-04 22:45:46.382029 AppName[1387:639346] Stack Trace: (
0 CoreFoundation 0x0000000192d981d8 <redacted> + 148
1 libobjc.A.dylib 0x00000001917d055c objc_exception_throw + 56
2 CoreFoundation 0x0000000192d033dc <redacted> + 0
3 AppName 0x00000001001269bc -[ListViewController tableView:cellForRowAtIndexPath:] + 512
4 UIKit 0x0000000198f243d4 <redacted> + 716
5 UIKit 0x0000000198f24604 <redacted> + 80
6 UIKit 0x0000000198f11bac <redacted> + 2304
7 UIKit 0x0000000198f29668 <redacted> + 116
8 UIKit 0x0000000198cc5b14 <redacted> + 176
9 UIKit 0x0000000198bde54c <redacted> + 1196
10 QuartzCore 0x00000001960a640c <redacted> + 148
11 QuartzCore 0x000000019609b0e8 <redacted> + 292
12 QuartzCore
2016-10-04 22:45:46.382306 AppName[1387:639346] -[_UITableViewReorderingSupport _needsSetup]: unrecognized selector sent to instance 0x170290e00
2016-10-04 22:45:46.382714 AppName[1387:639346] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_UITableViewReorderingSupport _needsSetup]: unrecognized selector sent to instance 0x170290e00'
*** First throw call stack:
(0x192d981c0 0x1917d055c 0x192d9f278 0x192d9c278 0x192c9659c 0x198d22c6c 0x198f24440 0x198f24604 0x198f11bac 0x198f29668 0x198cc5b14 0x198bde54c 0x1960a640c 0x19609b0e8 0x19609afa8 0x196017c64 0x19603f0d0 0x19603faf0 0x192d457dc 0x192d4340c 0x192d4389c 0x192c72048 0x1946f5198 0x198c4c628 0x198c47360 0x10015aaa8 0x191c545b8)
libc++abi.dylib: terminating with uncaught exception of type NSException
答案 0 :(得分：0)
2016-10-04 22:45:46.373274 AppName[1387:639346] Caught exception in cellForRowAtIndexPath
2016-10-04 22:45:46.373383 AppName[1387:639346] CRASH: *** -[__NSArray0 objectAtIndex:]: index 0 beyond bounds for empty NSArray
说它就在那里！在cellForRowAtIndexPath您尝试访问空0
NSArray
不要这样做，它不会崩溃！