UIPickerView 中的另一个 JSON 数据

Question

我查看了一些其他示例，但我似乎仍然无法弄清楚为什么我的pickerView 保持空白。

JSON 文件

{
"artstyle": [
             {
             "id": 1001,
             "name": "Plain",
             "prefix": "plain"
             },
             {
             "id": 1002,
             "name": "Brushed",
             "prefix": "brushed"
             },
             {
             "id": 1003,
             "name": "Swirly",
             "prefix": "swirly"
             }
             ]}

.h

@interface FlipScrollViewController : UIViewController <UIPickerViewDataSource,UIPickerViewDelegate>

@property NSArray *artArray;

@end

.m

@interface FlipScrollViewController ()

@end

@implementation FlipScrollViewController


- (void)viewDidLoad
{
    [super viewDidLoad];

    //Getting the file path from the local bundle.
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"art" ofType:@"json"];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData* data = [NSData dataWithContentsOfFile:filePath];
        [self performSelectorOnMainThread:@selector(fetchedData:)
                               withObject:data waitUntilDone:YES];
    });

}
- (void)fetchedData:(NSData *)responseData {
    //parse out the json data
    NSError* error;


    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];

    //self.artArray = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
    //NSLog(@"get: %@", _artArray);


   //NSArray* shapeguide = [json objectForKey:(@"artstyle")];
    // this spits out the whole JSON file contents
    //NSLog(@"Guide: %@", shapeguide);

    //NSDictionary *art = [shapeguide objectAtIndex:0];
    //NSLog(@"Guide: %@", guide);
    // Displays the "name" value in the Label text

    //name.text = [NSString stringWithFormat:@"%@",[guide objectForKey:@"name"]];

    //self.artArray = [art objectForKey:@"name"];

  _artArray = [json objectForKey:(@"name")];
    //NSLog(@"Guide: %@", _artArray);
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return 1;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
    return [_artArray count];
}

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
    return [_artArray objectAtIndex:row];
}

/*
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return 1;
}
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component

{
    //to do
    return [self.artArray count];
}

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{

    return [[self.artArray objectAtIndex:row] valueForKey:@"name"];

}
 */

@end

我知道我已经正确设置了委托，并且我知道 JSON 数据被正确吐出。我已经将 NSLogs 放在不同的地方进行检查。您可以从 .m 的部分内容中看到，我已经尝试了很多不同的方法来让这个东西正常工作。

我已经在这上面花了几天时间，我的头发都快用完了。另外，它看起来很臃肿，所以任何清理它的技巧都会受到赞赏。谢谢

Answer 1

- (void)fetchedData:(NSData *)responseData {
//parse out the json data
NSError* error;


NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];

NSLog(@"Guide: %@", json);

_artArray = [json objectForKey:@"artstyle"];

[<picker> reloadAllComponents];
}

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
NSDictionary *dict = [_artArray objectAtIndex:row];
NSLog(@"dict: %@", dict);
return [dict objectForKey:@"name"];
}

Answer 2

您正在以 ASYNCHRONOUS 形式检索 json 数据。

希望您在完成后忘记致电reloadAllComponents。

例如：

- (void)fetchedData:(NSData *)responseData {
// ........All your stuff
[pickerView reloadAllComponents] ;
}