这是我的代码ViewController.h
:
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
{
IBOutlet UITableView *mainTableView;
NSArray *news;
NSMutableData *data;
}
@end
这是ViewController.m
:
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = @"News";
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
NSURL *url = [NSURL URLWithString:@"http://google.com/external/search?query=hello"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[[NSURLConnection alloc] initWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
data = [[NSMutableData alloc] init];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)theData
{
[data appendData:theData];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
NSArray *responseDict = [NSJSONSerialization JSONObjectWithData:data options:nil error:nil];
news = [responseDict objectAtIndex:0];
[mainTableView reloadData];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
UIAlertView *errorView = [[UIAlertView alloc] initWithTitle:@"Error" message:@"The download could not complete - please make sure you're connected to either 3G or Wi-Fi." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil];
[errorView show];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}
- (int)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (int)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [news count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MainCell"];
if(cell == nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"MainCell"];
}
cell.textLabel.text = [[news objectAtIndex:indexPath.row] objectForKey:@"metaScore"];
cell.detailTextLabel.text = [[news objectAtIndex:indexPath.row] objectForKey:@"title"];
return cell;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
据我所知,将 JSON 放入字典的代码是错误的,因为它试图找到一个不存在的索引。有没有办法更改此代码,以便它可以将 JSON 数组读入字典?
更新:这是我的 .m 文件中的新代码:
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = @"News";
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
NSURL *url = [NSURL URLWithString:@"http://google.com/external/search?query=hello"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection connectionWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
data = [[NSMutableData alloc] init];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)theData
{
[data appendData:theData];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
NSArray *responseDict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:NULL];
//news = [responseDict objectAtIndex:0];
// [mainTableView reloadData];
if ([responseDict isKindOfClass:[NSArray class]]) {
news = responseDict;
[mainTableView reloadData];
} else {
NSLog(@"JSON Error.");
}
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
UIAlertView *errorView = [[UIAlertView alloc] initWithTitle:@"Error" message:@"The download could not complete - please make sure you're connected to either 3G or Wi-Fi." delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil];
[errorView show];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}
- (int)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (int)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [news count];
}
NSString *_getString(id obj)
{
return [obj isKindOfClass:[NSString class]] ? obj : nil;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MainCell"];
if(cell == nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"MainCell"];
}
cell.textLabel.text = _getString([[news objectAtIndex:indexPath.row] objectForKey:@"metaScore"]);
cell.detailTextLabel.text = _getString([[news objectAtIndex:indexPath.row] objectForKey:@"title"]);
return cell;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end