Objective-C

Firebase GET - Reading Data

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Demonstrates how to read parts of a Firebase JSON database. The data used in this example is at Chilkat Firebase Pigs Database, and is shown here:

Objective-C

#import <CkoFileAccess.h>
#import <NSString.h>
#import <CkoRest.h>
#import <CkoAuthGoogle.h>
#import <CkoStringBuilder.h>
#import <CkoJsonObject.h>

BOOL success = NO;

// Demonstrates how to read parts of a Firebase JSON database.

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example assumes a JWT authentication token, if required, has been previously obtained.
// See Get Firebase Access Token from JSON Service Account Private Key for sample code.

// Load the previously obtained Firebase access token into a string.
CkoFileAccess *fac = [[CkoFileAccess alloc] init];
NSString *accessToken = [fac ReadEntireTextFile: @"qa_data/tokens/firebaseToken.txt" charset: @"utf-8"];
if (fac.LastMethodSuccess != YES) {
    NSLog(@"%@",fac.LastErrorText);
    return;
}

CkoRest *rest = [[CkoRest alloc] init];

// Make the initial connection (without sending a request yet).
// Once connected, any number of requests may be sent.  It is not necessary to explicitly
// call Connect before each request.  
success = [rest Connect: @"chilkat.firebaseio.com" port: [NSNumber numberWithInt: 443] tls: YES autoReconnect: YES];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// If authentication is required...
CkoAuthGoogle *authGoogle = [[CkoAuthGoogle alloc] init];
authGoogle.AccessToken = accessToken;
[rest SetAuthGoogle: authGoogle];

// Chilkat's sample data (pig-rescue data) is publicly readable at: https://chilkat.firebaseio.com/.json

// Let's get the animals with the shallow parameter so we can see how many pigs exist.
NSString *jsonResponse = [rest FullRequestNoBody: @"GET" uriPath: @"/pig-rescue/animal.json?shallow=true"];
if (rest.LastMethodSuccess != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// The JSON returned should look like this:  
// {"-KI3bD-FU_Dake7sYOiP":true,"-KI3bD-FU_Dake7sYOiT":true,"-KI3bD-FU_Dake7sYOiS":true,"-KI3bD-FU_Dake7sYOiU":true,"-KI3bD-FU_Dake7sYOiV":true,"-KI3bD-FU_Dake7sYOiR":true,"-KI3bD-FU_Dake7sYOiQ":true}
NSLog(@"%@",jsonResponse);

// Parse the response so we can iterate over each pig in the database..
CkoStringBuilder *piggyPath = [[CkoStringBuilder alloc] init];
CkoJsonObject *shallow = [[CkoJsonObject alloc] init];
CkoJsonObject *piggyData = [[CkoJsonObject alloc] init];
[shallow Load: jsonResponse];
int count = [shallow.Size intValue];
int i = 0;
while (i < count) {

    // Get each individual pig's data.
    [piggyPath Clear];
    [piggyPath Append: @"/pig-rescue/animal/"];
    [piggyPath Append: [shallow NameAt: [NSNumber numberWithInt: i]]];
    [piggyPath Append: @"/.json"];

    NSString *piggyJson = [rest FullRequestNoBody: @"GET" uriPath: [piggyPath GetAsString]];
    if (rest.LastMethodSuccess != YES) {
        NSLog(@"%@",rest.LastErrorText);
        return;
    }

    // Show this piggy's data...
    // An example of one pig's data is shown here:
    // {"birth":"February, 1998","from":"Middle Ave.","gender":"F","in-date":"January, 2000",
    //   "name":"Molly II","picture":{"caption":"Molly in the Pasture","description":"Black pig","file":"molly_th.jpg"},
    //   "species":"pot belly pig","type":"Cathy's Herd"}
    NSLog(@"%@%d%@",@"---- ",i,@" ----");
    NSLog(@"%@",piggyJson);

    // Let's get the pig's name, and the caption of the picture.
    [piggyData Load: piggyJson];
    NSLog(@"%@%@",@"name: ",[piggyData StringOf: @"name"]);
    NSLog(@"%@%@",@"caption: ",[piggyData StringOf: @"picture.caption"]);

    i = i + 1;
}

// Note: In many of the Chilkat examples, you may notice strange ways
// of doing something that should be simpler and shorter.  For example,
// building the piggyPath (above) could've been written differently,
// with some simple string concatenation.
// 
// The reason is that the Chilkat examples are written in a 
// proprietary "example code" scripting language,
// and then automatically generated to each of the different programming
// languages you see on example-code.com.  The code generation is
// limited in what it can do.  For example, string concatentation
// is not yet a feature of the "example code" scripting language (as of May 2016), 
// and therefore you won't see the use of a programming language's string
// concatentation operators in any example.  
//