Question

我需要从Parse API查询一些数据。下面的代码是Parse的CURL示例：

curl -X GET \
  -H "X-Parse-Application-Id: XXXXX" \
  -H "X-Parse-REST-API-Key: XXXXX" \
  -G \
  --data-urlencode 'where={"key1":"value1","key2":"value2"}' \
  https://api.parse.com/1/classes/ClassName

然后，这是我的代码：

NSDictionary *dictionary = @{@"key1": @"value1", @"key1": @"value2"};
NSError *error = nil;
NSString *jsonString = nil;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:kNilOptions error:&error];

if (!jsonData)
    NSLog(@"Got an error: %@", error);
else
    jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

NSString *fullUrl = [NSString stringWithFormat:@"https://api.parse.com/1/classes/ClassName?where=%@", jsonString];

NSURL *url = [NSURL URLWithString:fullUrl];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"GET"];
[request addValue:@"XXXXX" forHTTPHeaderField:@"X-Parse-Application-Id"];
[request addValue:@"XXXXX" forHTTPHeaderField:@"X-Parse-REST-API-Key"];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    if (!error) {
        NSLog(@"Data: %@", data);
        NSLog(@"Response: %@", response);
    }else{
        NSLog(@"Error: %@", error);
    }
}];
[task resume];

执行后，我遇到了一些错误：

2015-01-16 18:19:57.532 ParseTest[37964:1018046] 
Error: Error Domain=NSURLErrorDomain Code=-1002 
"The operation couldn’t be completed. (NSURLErrorDomain error -1002.)" 
UserInfo=0x7d17d320 {NSUnderlyingError=0x7d051f70 "The operation couldn’t be completed. (kCFErrorDomainCFNetwork error -1002.)"}

完成过去的CURL代码的Objective-C等价物是什么？或者你的建议是什么？

提前致谢。

Answer 1

您需要使用PFQuery。有关信息，请参阅Parse's iOS/OS X Documentation。

这是一些用于执行上述尝试的示例代码。它应该是该cURL代码的直接替代品：

- (void)runQuery {
    PFQuery *query = [PFQuery queryWithClassName:@"ClassName"];
    [query whereKey:@"key1" equalTo:value1];
    [query whereKey:@"key2" equalTo:value2];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (error != nil) {
            // Do error handling here

        } else {
            // You have a valid query result

        }
    }
     ];
}

请不要忘记，您需要在应用中初始化Parse连接，然后才能拨打电话。这样，您就不需要像在cURL代码中那样传递每个请求的密钥。您可以在AppDelegate对象的-didFinishLaunchingWithOptions:方法中执行此操作，如下所示：

#import <Parse/Parse.h>
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Initialize Parse.
    [Parse
      setApplicationId:@"<App Id>"
      clientKey:@"<Client Key>"];

}

Answer 2

NSURLErrorDomain error -1002表示不支持该网址。我的猜测是你需要对json的where参数进行URL编码。也许改变你的URL：

if (!jsonData)
    NSLog(@"Got an error: %@", error);
else
    jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

jsonString = [jsonString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString *fullUrl = [NSString stringWithFormat:@"https://api.parse.com/1/classes/ClassName?where=%@", jsonString];

如果这不起作用，您是否尝试过登录fullUrl并尝试cURL它？

使用Objective-C发送HTTP GET请求

2 个答案: