UIPickerView是一个选择器它可以生成单列的选择器,也可生成多列的选择器,而且开发者完全可以自定义选择项的外观,因此用法非常灵活,使用也比较简单.下面做了一个关于天气预报的小Demo 用 UIPickerView 来实现.

@property (strong, nonatomic) NSDictionary *dataDic;

@property (strong, nonatomic) NSArray *cityArr;

@end

@implementation ViewController
- (void)viewDidLoad {

    [super viewDidLoad];
    _grayView.hidden = YES;
    
    // 1.初始化 pickerView
    [self loadPickerView];
    
    // 2.加载网络数据
    [self loadDataWithRow:0];
    
}

- (void)loadPickerView
{

    // 读取本地plist文件
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"cityCode.plist" ofType:nil];
    
    _dataDic = [[NSDictionary alloc] initWithContentsOfFile:filePath];
    
    // 拿到 key <城市>
    _cityArr = [_dataDic allKeys];   
}

- (void)loadDataWithRow:(NSInteger)row
{

    _grayView.hidden = NO;
    
    // 1.获取当前的城市下标
//    NSInteger selectRow = [_pickerView selectedRowInComponent:0];
   
    // 2.通过下标获取城市
    NSString *city = _cityArr[row];
    
    // 3.获取当前城市的ID
    NSString *cityID = _dataDic[city];
    
    // 4.通过城市ID加载数据
    NSString *httpURL = [NSString stringWithFormat:@"data/sk/%@.html", cityID];
    
    [DataService requestsDataWithURL:httpURL withBlock:^(id result) {
        [self performSelector:@selector(showGrayView:) withObject:result afterDelay:.2];
    }];   
}

// 无敌风火轮动画
- (void)showGrayView:(id)result
{

//    _grayView.hidden = NO;

//    [_activiteView startAnimating];
    
      [self performSelector:@selector(refreshUIWithDic:) withObject:result afterDelay:2];
}

//刷新UI
- (void)refreshUIWithDic:(NSDictionary *)dic {
    
    _grayView.hidden = YES;
    //取得weatherinfo的value
    NSDictionary *infoDic = dic[@"weatherinfo"];
    
    //取得城市信息
    _city.text = infoDic[@"city"];

    //取得城市温度
    _temperature.text = infoDic[@"temp"];

    //取得城市的风向
    _wind.text = infoDic[@"WD"];

    //取得城市的风级
    _windScale.text = infoDic[@"WS"];

    //取得城市的湿度
    _humidity.text = infoDic[@"SD"];
        
    //取得城市的时间
    _time.text = infoDic[@"time"];
    
    
}

#pragma mark - UIPickerViewDataSource
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{

      return 1;  // 多少列
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{

      return _cityArr.count; // 每一列多少行
}


#pragma mark - UIPickerViewDelegate
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{

      // 设置没一行显示的数据
      return _cityArr[row];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{

      // 刷新
      [self loadDataWithRow:row];
}

数据解析:

#define FIRSTURL   @"http://www.weather.com.cn/"

@implementation HCDataService
+ (void)requestsDataWithURL:(NSString *)urlString withBlock:(DataBlock)block
{
          
// 1.创建URL
    NSString *string = [NSString stringWithFormat:@"%@%@", FIRSTURL, urlString];
    NSURL *url = [NSURL URLWithString:string];
    
    // 2.创建request
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];

    // 设置请求方式
    [request setHTTPMethod:@"GET"];

    // 设置超时时间
    request.timeoutInterval = 10;
    
    // 3.创建会话对象session
    NSURLSession *session = [NSURLSession sharedSession];
    
    // 4.创建会话任务task,链接服务器
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error == nil) {
            dispatch_async(dispatch_get_main_queue(), ^{
                id result = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
                block(result);
            });
            
            //取得响应体
//            NSString *text = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

//            NSLog(@"%@", text);
            
            //取得响应头
//            NSHTTPURLResponse *urlResponse = (NSHTTPURLResponse *)response;

//            NSDictionary *dic = urlResponse.allHeaderFields;

//            NSLog(@"dic:%@",dic);

        }
    }];
      // 开始任务
      [task resume];
}
@end

滑动了UIPickView后，数据会即时刷新，显示天气情况。

123.gif