如何更改 sendSynchronousRequest:urlRequest 因为已弃用

Question

我是 Objective - C 的初学者，我有一个方法

- (void)getAltitudeFromElevationFromAlt:(float)latitude Long:(float)longitude{
    dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSString *apiKey = @"IzaSyA5CDPUYC7GY5PzJdu_K4ouRy55gm3R5BO4";
        NSString *address = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/elevation/json?locations=%f,%f&key=%@", latitude, longitude, apiKey];
        // Send a synchronous request

        NSURLRequest * urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:address]];
        NSURLResponse * response = nil;
        NSError * error = nil;
        NSData * data = [NSURLConnection sendSynchronousRequest:urlRequest
                                              returningResponse:&response
                                                          error:&error];

       NSString *str = @"No Data";
        if (error == nil)
        {
            NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
            str = [NSString stringWithFormat:@"%@", dictionary[@"results"][0][@"elevation"]];
            //  NSLog(@"text  = %@", dictionary[@"results"][0][@"elevation"]);
            NSLog(@"str = %@", str);
            dispatch_async( dispatch_get_main_queue(), ^{
                _altitudeMeterLabel.text = str;
            });
        }
    });
}

请帮助更改此顺序

NSData * data = [NSURLConnection sendSynchronousRequest:urlRequest
                                          returningResponse:&response
                                                      error:&error];

Answer 1

使用NSURLSession和异步请求：

- (void)getAltitudeFromElevationFromAlt:(float)latitude Long:(float)longitude {

   NSString *apiKey = @"IzaSyA5CDPUYC7GY5PzJdu_K4ouRy55gm3R5BO4";
   NSString *address = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/elevation/json?locations=%f,%f&key=%@", latitude, longitude, apiKey];
   // Send an ASYNCHRONOUS request

   NSURLRequest * urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:address]];
   [[[NSURLSession sharedSession] dataTaskWithRequest:urlRequest completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
      NSString *str = @"No Data";
      if (error) {
         NSLog(@"%@", error);
      } else {
         NSError * jsonError = nil;
         NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&jsonError];
         if (jsonError) {
            NSLog(@"%@", jsonError);
         } else {
            str = [NSString stringWithFormat:@"%@", dictionary[@"results"][0][@"elevation"]];
            //  NSLog(@"text  = %@", dictionary[@"results"][0][@"elevation"]);
            NSLog(@"str = %@", str);
         }
         dispatch_async( dispatch_get_main_queue(), ^{
            _altitudeMeterLabel.text = str;
         });
      }
   }] resume];
}

注：

不需要全局 dispatch_async 块，因为数据任务无论如何都会分派到后台线程。

Answer 2

将 NSURLSession 与 dataTaskWithRequest

结合使用

- (void)getAltitudeFromElevationFromAlt:(float)latitude Long:(float)longitude
{
    NSString *apiKey = @"IzaSyA5CDPUYC7GY5PzJdu_K4ouRy55gm3R5BO4";
    NSString *address = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/elevation/json?locations=%f,%f&key=%@", latitude, longitude, apiKey];

    NSURLRequest * request = [NSURLRequest requestWithURL:[NSURL URLWithString:address]];
    NSURLResponse * response = nil;
    NSString *str = @"No Data";

    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request
                                         completionHandler:
     ^(NSData *data, NSURLResponse *response, NSError *error) {
    if (error == nil)
    {
        NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
        str = [NSString stringWithFormat:@"%@", dictionary[@"results"][0][@"elevation"]];
        //  NSLog(@"text  = %@", dictionary[@"results"][0][@"elevation"]);
        NSLog(@"str = %@", str);
        dispatch_async( dispatch_get_main_queue(), ^{
            _altitudeMeterLabel.text = str;
        });
    }
    }];

     [task resume];    
}

Answer 3

请尝试以下代码

    - (void)getAltitudeFromElevationFromAlt:(float)latitude Long:(float)longitude{
dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    NSString *apiKey = @"IzaSyA5CDPUYC7GY5PzJdu_K4ouRy55gm3R5BO4";
    NSString *address = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/elevation/json?locations=%f,%f&key=%@", latitude, longitude, apiKey];
   // Send a synchronous request

    NSURLSession *session = [NSURLSession sharedSession];
    [[session dataTaskWithURL:[NSURL URLWithString:address]
            completionHandler:^(NSData *data,
                                NSURLResponse *response,
                                NSError *error) {
                NSString *str = @"No Data";
                if (error == nil)
                {
                    NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
                    str = [NSString stringWithFormat:@"%@", dictionary[@"results"][0][@"elevation"]];
                    //  NSLog(@"text  = %@", dictionary[@"results"][0][@"elevation"]);
                    NSLog(@"str = %@", str);
                    dispatch_async( dispatch_get_main_queue(), ^{
                        _altitudeMeterLabel.text = str;
                    });
                }

            }] resume];
    });

}

Answer 4

从 iOS9 开始不推荐使用同步方法，因为它会阻塞主线程。所以不建议同步执行这个操作。

如果确实需要，您可以创建 NSUrlSession 类别来同步执行您的请求。

#import "NSURLSession+Sync.h"

@implementation NSURLSession (Sync)

+ (NSData *)sendSynchronousRequest:(NSURLRequest *)request
                 returningResponse:(__autoreleasing NSURLResponse **)responsePtr
                             error:(__autoreleasing NSError **)errorPtr {
    dispatch_semaphore_t    sem;
    __block NSData *        result;

    result = nil;

    sem = dispatch_semaphore_create(0);

    [[[NSURLSession sharedSession] dataTaskWithRequest:request
                                     completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                         if (errorPtr != NULL) {
                                             *errorPtr = error;
                                         }
                                         if (responsePtr != NULL) {
                                             *responsePtr = response;
                                         }  
                                         if (error == nil) {  
                                             result = data;  
                                         }  
                                         dispatch_semaphore_signal(sem);  
                                     }] resume];  

    dispatch_semaphore_wait(sem, DISPATCH_TIME_FOREVER);  

    return result;  
}
@end

并在如下代码中使用：

  NSData * data = [NSURLSession sendSynchronousRequest:urlRequest returningResponse:&response error:&error];

如何更改 sendSynchronousRequest:urlRequest 因为已弃用

How to change sendSynchronousRequest:urlRequest because is Deprecated

objective-c

deprecated

ios