Question

我试图让搜索过滤器适用于我的tableview，当我点击搜索栏并且返回此错误时，它会崩溃应用程序

2014-03-30 14：44：08.676 BookStore [16156：90b] *由于未捕获的异常'NSInvalidArgumentException'终止应用程序，原因：' - [PFObject rangeOfString：options：]：发送到实例的无法识别的选择器0x9da1a40' * 首先抛出调用堆栈：

这是代码：

//
//  PDFTableViewController.m
//  BookStore
//
//  Created by Danijel Kujundzic on 3/23/14.
//  Copyright (c) 2014 Danijel Kujundzic. All rights reserved.
//

#import "PDFTableViewController.h"
#import "PDFDetailViewController.h"
@interface PDFTableViewController ()<UISearchBarDelegate , UISearchDisplayDelegate>
{
  NSMutableArray * filteredStrings;
    BOOL isFiltered;
}

@end

@implementation PDFTableViewController




@synthesize PDFtableView;


- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self performSelector:@selector(RetrievePDFParseData)];
    self.SearchBar.delegate =self;
    self.PDFtableView.delegate=self;
    self.PDFtableView.dataSource =self;
    filteredStrings = [[NSMutableArray alloc] initWithArray:PDFArray];
}



- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
    if (searchText.length ==0) {
        isFiltered= NO;
        [filteredStrings removeAllObjects];
        [self.tableView reloadData];
        [searchBar resignFirstResponder];
    }
    else
    {
        isFiltered = YES;
        if([PDFArray count]!=0)
        {
            NSPredicate *p=[NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
                NSString *s=evaluatedObject;
                return ([s rangeOfString:searchBar.text options:NSCaseInsensitiveSearch].location !=NSNotFound);
            }];
            filteredStrings= [NSMutableArray arrayWithArray:[PDFArray filteredArrayUsingPredicate:p]];
            //table reload
            [self.tableView reloadData];
        }

    }
}




-(void) RetrievePDFParseData {
    PFQuery * getPDF = [PFQuery queryWithClassName:@"PDFTableView"];

    [getPDF findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if(!error) {
           PDFArray =[[NSArray alloc] initWithArray: objects];

        }
        [PDFtableView reloadData];

    }];

}




- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

#pragma mark - Table view data source





- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if (isFiltered) {
        return [filteredStrings count];
    }


    return [PDFArray count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString * CellIdentifier = @"Cell";
        UITableViewCell * cell = [PDFtableView dequeueReusableCellWithIdentifier:CellIdentifier];

        if (cell ==nil) {
            cell = [[ UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"Cell"];
        }

        if (!isFiltered) {
            PFObject * tempObject = [PDFArray objectAtIndex:indexPath.row];
            cell.textLabel.text = [tempObject objectForKey:@"PDFName"];
            cell.detailTextLabel.text= [tempObject objectForKey:@"Author"];
        }

        if (isFiltered)


        {
            PFObject *filteredObject= [[filteredStrings objectAtIndex:indexPath.row]initWithArray:PDFArray];
            cell.textLabel.text =[filteredObject objectForKey:@"PDFName"];
            cell.detailTextLabel.text= [filteredObject objectForKey:@"Author"];
            NSLog(@"%@", filteredObject);
        }


        return cell;

    }


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    [self performSegueWithIdentifier:@"detailSegue" sender:self];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{

    if([segue.identifier isEqualToString:@"detailSegue"]){

        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
        PDFDetailViewController *detailVC = (PDFDetailViewController *)segue.destinationViewController;
        NSLog(@"Bookarray=%@", PDFArray);
        NSLog(@"BookIndex=%@", [PDFArray objectAtIndex:indexPath.row]);
        detailVC.PDFna=[[PDFArray objectAtIndex:indexPath.row]objectForKey:@"PDFName"];
        detailVC.PDFdes= [[PDFArray objectAtIndex:indexPath.row]objectForKey:@"About"];
        detailVC.downloadfile=[[PDFArray objectAtIndex:indexPath.row]objectForKey:@"PDFFile"];


    }
}


@end

Answer 1

您认为是NSStrings的对象数组实际上是PFObjects。 PDFArray包含一个PFObject数组。您可能想要在UISearchBarDelegate方法中创建的谓词中抓取某个属性，

-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText

像NSString *s = evaluatedObject[@"PDFName"];这样的东西，或其他类似的东西会使你实际上过滤PDF文件的名称。

Answer 2

错误在searchBar:textDidChange:方法中。在这种情况下，谓词返回PFObject，而不是NSString。因此，您必须在evaluatedObject对象中搜索您需要的NSString对象。

这些是有问题的行：

NSString *s=evaluatedObject;
return ([s rangeOfString:searchBar.text options:NSCaseInsensitiveSearch].location !=NSNotFound);

rangeOfString引发了异常，因为PFObject没有回复rangeOfString。

在其他语言中，编译器有时会警告您这种情况。在Objective-C中，在处理任何类型的对象时必须小心：id。如果特定对象在编译时响应消息，则编译器不会进行检查。但是当Objective-C运行时在运行时执行此操作时，会出现崩溃。

在Objective-C中阅读有关对象和消息的更多信息： https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/WorkingwithObjects/WorkingwithObjects.html

这个错误是什么意思？

2 个答案: