[英]JSON parsing returns null to iOS (json string looks correct)
我正在嘗試將JSON轉換為iOS應用,但始終獲取NULL值。
- (id)initWithDictionary:(NSDictionary *)dictionary { self.name = [dictionary valueForKey:@"name"]; self.amount = [NSString stringWithFormat:@"%@", [dictionary valueForKey:@"amount"]]; self.goalId = [dictionary valueForKey:@"id"]; self.createdAt = [dictionary valueForKey:@"created_at"]; self.updatedAt = [dictionary valueForKey:@"updated_at"]; return self; } + (NSArray *)findAllRemote { NSURL *url = [NSURL URLWithString:@"http://localhost:3000/goals.json"]; NSError *error = nil; NSString *jsonString = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:&error]; NSLog(@"my string = %@", jsonString); NSMutableArray *goals = [NSMutableArray array]; if (jsonString) { SBJSON *json = [[SBJSON alloc] init]; NSArray *results = [json objectWithString:jsonString error:&error]; [json release]; for (NSDictionary *dictionary in results) { Goal *goal = [[Goal alloc] initWithDictionary:dictionary]; [goals addObject:goal]; [goal release]; } } return goals; }
JSON字符串看起來正確:
我的字符串= [{“目標”:{“數量”:“ 100.0”,“ created_at”:“ 2011-08-20T00:55:34Z”,“ id”:1,“名稱”:“用戶”,“ updated_at “:” 2011-08-20T00:55:34Z“}},{”目標“:{”金額“:” 200.0“,” created_at“:” 2011-08-20T00:56:48Z“,” id“: 2,“名稱”:“ User2”,“ updated_at”:“ 2011-08-20T00:56:48Z”}},{“目標”:{“金額”:“ 19999.0”,“ created_at”:“ 2011-08 -20T19:15:10Z“,” id“:3,”名稱“:”這是我的目標“,” updated_at“:” 2011-08-20T19:15:10Z“}},{”目標“:{”數量“:” 0.0“,” created_at“:” 2011-08-20T20:46:44Z“,” id“:4,”名稱“:”目標“,” updated_at“:” 2011-08-20T20:46: 44Z“}}]
我想念一些基本的東西。
更新 :
這是一行返回NULL(從另一個類)的行:
- (IBAction)refresh {
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
self.goals = [Goal findAllRemote];
[self.tableView reloadData];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = @"Goals";
self.navigationItem.leftBarButtonItem = self.editButtonItem;
UIBarButtonItem *refreshButton = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh
target:self
action:@selector(refresh)];
self.navigationItem.rightBarButtonItem = refreshButton;
[refreshButton release];
[self refresh];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"GoalCellId";
UITableViewCell *cell =
[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1
reuseIdentifier:CellIdentifier] autorelease];
}
Goal *goal = [goals objectAtIndex:indexPath.row];
cell.textLabel.text = goal.name;
cell.detailTextLabel.text = goal.amount;
return cell;
}
目標名稱和目標金額為空。
這可能不是問題的一部分,但您應該調用[self init]
(或更重要的是,通過繼承調用[super init]
):
- (id)initWithDictionary:(NSDictionary *)dictionary {
if (self = [self init]) {
self.name = [dictionary valueForKey:@"name"];
self.amount = [NSString stringWithFormat:@"%@",
[dictionary valueForKey:@"amount"]];
self.goalId = [dictionary valueForKey:@"id"];
self.createdAt = [dictionary valueForKey:@"created_at"];
self.updatedAt = [dictionary valueForKey:@"updated_at"];
}
return self;
}
也:
for (NSDictionary *dictionary in results) {
Goal *goal = [[Goal alloc] initWithDictionary:
[dictionary objectForKey:@"goal"]];
[goals addObject:goal];
[goal release];
}
密鑰更改是第3行中的[dictionary objectForKey:@"goal"]
。
JSON數組由具有單個goal
成員的對象組成,具有initWithDictionary
方法要查找的屬性。
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