Question

我是Objective-C的新手。我正在尝试创建一个天气应用程序，我从开放的天气图解析数据。我已将解析后的数据存储到数组中。现在想要从其他类访问数组值但是获取空值。

任何人都可以帮助我吗？

我尝试过：

这是我的NSObject类，我在那里存储数据并尝试将其发送给视图控制器：

- (void)getCurrentWeather:(NSString *)query
{
    NSString *const BASE_URL_STRING = @"http://api.openweathermap.org/data/2.5/weather?q=";
    NSString *const API_KEY = @"&APPID=APIKEYSTRING";

    NSString *weatherURLText = [NSString stringWithFormat:@"%@%@%@",
    BASE_URL_STRING, query,API_KEY];
    NSURL *weatherURL = [NSURL URLWithString:weatherURLText];

    dispatch_async(kBgQueue, ^{
    NSData* data = [NSData dataWithContentsOfURL:weatherURL];
    [self performSelectorOnMainThread:@selector(fetchedDataSmile | :) withObject:data waitUntilDone:YES];

    });
}

- (void)fetchedData:(NSData *)responseData {
    NSError* error;
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];

    NSString* cityName = [json objectForKey:@"name"];

    int currentTempCelsius = (int)[[[json objectForKey:@"main"] objectForKey:@"temp"] intValue] - ZERO_CELSIUS_IN_KELVIN;
    int maxTemp = (int)[[[json objectForKey:@"main"] objectForKey:@"temp_max"] intValue] - ZERO_CELSIUS_IN_KELVIN;
    int minTemp = (int)[[[json objectForKey:@"main"] objectForKey:@"temp_min"] intValue] - ZERO_CELSIUS_IN_KELVIN;
    NSString *weatherDescription = [[[json objectForKey:@"weather"] objectAtIndexBlush | :O ] objectForKey:@"description"];

    weatherArray = [[NSMutableArray alloc] initWithObjects:cityName, weatherDescription,
    [NSString stringWithFormat:@"%d", currentTempCelsius],
    [NSString stringWithFormat:@"%d", maxTemp],
    [NSString stringWithFormat:@"%d", minTemp],nil];

我有NSObject.h文件：

@interface WeatherData : NSObject

@property (nonatomic) NSString *weatherDescription;
@property (strong, nonatomic) NSString *currentTemp;
@property (nonatomic) int maxTempCelsius;
@property (nonatomic) int minTempCelsius;
@property (nonatomic, retain) NSMutableArray *weatherArray;

- (void)getCurrentWeather:(NSString *)query;

@end

在我的视图控制器中：

.h文件：

@property (nonatomic, retain) NSMutableArray *weatherResultArray;

.m文件：

-(void)searchButtonClicked:(UIButton*)sender
{
    [self.view endEditing:YES];
    WeatherData *weather = [[WeatherData alloc] init];
    [weather getCurrentWeather:_textField.text];
    self.weatherResultArray = weather.weatherArray;

    //temperatureLabel.text = [NSString stringWithFormat:@"%d°",weather.currentTempCelsius];
}

我只想在UILabel中显示结果。

Answer 1

您是否尝试在此方法中返回NSMutable数组

- (NSMutableArray*)getCurrentWeather:(NSString *)query

而不是这个，

- (void)getCurrentWeather:(NSString *)query

这是验证的最简单方法，并且可以在单个语句中检索值：

self.weatherResultArray = [weather getCurrentWeather:_textField.text];

还有一点，不要忘记将weatherResultArray分配并初始化为：

self.weatherResultArray = [[NSMutableArray alloc]init];

Answer 2

在NSObject类中，定义天气协议。

//NSObject.h file
@protocol WeatherDelegate<NSObject>

-(void)getWeatherData:(YourNSObjectClass*)viewController getWeatherData:(NSMutableArray*)array;

@end

// NSObject.m文件，在

中

- (void)fetchedData:(NSData *)responseData {

NSError* error;
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
    NSString* cityName = [json objectForKey:@"name"];

    int currentTempCelsius = (int)[[[json objectForKey:@"main"] objectForKey:@"temp"] intValue] - ZERO_CELSIUS_IN_KELVIN;
    int maxTemp = (int)[[[json objectForKey:@"main"] objectForKey:@"temp_max"] intValue] - ZERO_CELSIUS_IN_KELVIN;
    int minTemp = (int)[[[json objectForKey:@"main"] objectForKey:@"temp_min"] intValue] - ZERO_CELSIUS_IN_KELVIN;
    NSString *weatherDescription = [[[json objectForKey:@"weather"] objectAtIndexBlush | :O ] objectForKey:@"description"];

    weatherArray = [[NSMutableArray alloc] initWithObjects:cityName, weatherDescription,
    [NSString stringWithFormat:@"%d", currentTempCelsius],
    [NSString stringWithFormat:@"%d", maxTemp],
    [NSString stringWithFormat:@"%d", minTemp],nil];

   id<WeatherDelegate> strongDelegate = self.delegate;

    if ([strongDelegate respondsToSelector:@selector(getWeatherData:getWeatherData:)])
    {
        [strongDelegate getWeatherData:self getWeatherData:weatherArray];
    }

}

在yourViewController类中，添加此WeatherData协议并在.m文件中添加委托函数以获取数据。

@interface yourViewControllerClass()<WeatherDelegate>
{
   YourNSObjectClass *nsClass;
   NSMutableArray *dataArray;
}

-(void)getWeatherData:(YourNSObjectClass*)viewController getWeatherData:(NSMutableArray*)array{

 dataArray = [[NSMutableArray alloc]initWithArray:array];

}

-(void)searchButtonClicked:(UIButton*)sender
{
    [self.view endEditing:YES];
    WeatherData *weather = [[WeatherData alloc] init];
    [weather getCurrentWeather:_textField.text];
    self.weatherResultArray = dataArray;

    //temperatureLabel.text = [NSString stringWithFormat:@"%d°",weather.currentTempCelsius];
}

如何将NSArray从NSObject类传递给UIViewController类？

2 个答案: