iOS开发,从网络中成功获取到数据源,却在UITableView中不显示,求解

网络获取的数据:
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代码:
#import "SecondViewController.h"

@interface SecondViewController ()

@property NSMutableData *mutableData;
@property NSString *string;
@property NSMutableArray *courses;

@end

@implementation SecondViewController

  • (void)viewDidLoad { NSString path = @"http://***************************"; NSURL *url = [NSURL URLWithString:path]; NSURLRequest *request = [NSURLRequest requestWithURL:url]; NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self]; [connection start]; [super viewDidLoad]; self.classBarItem.badgeValue = nil;

}

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

  • (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
    NSLog(@"%@", response);
    }

  • (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    if(_mutableData == nil){
    _mutableData = [[NSMutableData alloc]init];
    }
    [_mutableData appendData:data];
    }

  • (void)connectionDidFinishLoading:(NSURLConnection *)connection{
    _string = [[NSString alloc]initWithBytes:[_mutableData bytes] length:[_mutableData length] encoding:NSUTF8StringEncoding];
    NSJSONSerialization *json_courses = [NSJSONSerialization JSONObjectWithData:_mutableData options:0 error:nil];
    NSMutableDictionary *json = [NSJSONSerialization JSONObjectWithData:_mutableData options:0 error:nil];
    _courses = [[NSMutableArray alloc] init];
    for(int i = 0; i < [json count]; i++){
    NSString *tag = @"course";
    NSString *str_i = [[NSString alloc]initWithFormat:@"%i",i];
    tag = [tag stringByAppendingString:str_i];
    NSJSONSerialization *json_course = [json_courses valueForKey:tag];
    NSString *name = [json_course valueForKey:@"courseName"];
    NSLog(@"%@",name);
    [_courses addObject:name];
    }
    NSLog(@"%@",_courses);
    //获取NSMuTableArray中第n个元素的值
    //NSLog(@"%@", [_courses objectAtIndex:1]);
    _mutableData = nil;
    }

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

  • (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    NSLog(@"Array count is %i",[_courses count]);
    return [_courses count];
    }

    • (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
      UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"courses" forIndexPath:indexPath];
      cell.textLabel.text = [_courses objectAtIndex:[indexPath row]];
      // Configure the cell...

      return cell;
      }

/*
// Override to support conditional editing of the table view.

  • (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath { // Return NO if you do not want the specified item to be editable. return YES; } */

/*
// Override to support editing the table view.

  • (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the row from the data source [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade]; } else if (editingStyle == UITableViewCellEditingStyleInsert) { // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view } } */

/*
// Override to support rearranging the table view.

  • (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath { } */

/*
// Override to support conditional rearranging of the table view.

  • (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath { // Return NO if you do not want the item to be re-orderable. return YES; } */

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation

  • (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { // Get the new view controller using [segue destinationViewController]. // Pass the selected object to the new view controller. } */

@end

2个回答

个人分析是:该类先创建了tableview然后才获取网络数据源,可是不知道怎么解决

问题已经自行解决,原因如下:
由于获取网络数据并不在主线程中进行,所以程序会先执行后面的代码,最终导致程序虽然获得了数据源,却没有在tableview中显示出来。
此时只需要在connectionDidFinishLoading方法的末尾增加一句“[self.tableView reloadData];”来重载数据即可!

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