Overview and resources

The iOS SDK is available to developers who integrate iOS native client development and does not rely on any third-party libraries.

Environmental requirements

Item Resources
Development object Compatible with iOS 8+
Developing environment Xcode 13.0+
System dependent Webkit.framework
Third-party dependency of SDK None
Item Resources
Product structure process Communication process
SDK interface documentation gt4-api-ref-ios or view header file comments
Error code list Error Code List



Go to the dashboard to download the current SDK.

Import SDK

  1. If you add SDK manually, drag the downloaded GTCaptcha4.framework file into the project and make sure that “Copy items” is checked in case it is needed.

    Please import the framework using Linked Frameworks and Libraries method. After dragging GTCaptcha4.framework and ZXSDK-Noidfa.framework (for assisting risk assessment) into the project, check whether .framework has been added to PROJECT -> Build Phases -> Linked Frameworks and Libraries.


  2. As for Category in the static library, -ObjC needs to be added toBuild Settings->Other Linker Flags of the corresponding target.


  3. GT4Captcha4.Bundle needs to be included in the project at the same time, otherwise, verification will fail. Drag the GTCaptcha4.Bundle to the SDK path in the project.


Configure interface

As shown in the product workflow process, you need to set up Server interface in your backend first, and configure it with captchaId and Key you got from GeeTest dashbaord.

You need to use iOS SDK to complete the following iconfiguration:

  1. Use ID to set up initialization of CAPTCHA
  2. Start verification
  3. Get verification parameters and carry out secondary verification on the submitted result to avoid forgery
  4. Use the error proxy method to deal with problems that may be encountered during verification

Follow the GTCaptcha4SessionTaskDelegate protocol to manage verification results and errors that may be returned.

Refer to the code samples below for integration code.

Compile and run your project

Compile your project and experience GeeTest Adaptive CAPTCHA.


Sample code

Initialization and call CAPTCHA

Import the header file for verifying the dynamic library GTCaptcha4.framework in the project

#import <GTCaptcha4/GTCaptcha4.h>

Integration with UIButton

  1. Initialization

An instance of initialization validation manager GTCaptcha4Session, which calls the registration method of GTCaptcha4Session sample in the UIButton initialization method to obtain registration data:

#define captchaID @"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
@interface ViewController () <GTCaptcha4SessionTaskDelegate>
@property(strong, nonatomic) IBOutlet UIButton *startBtn;
@property(nonatomic, strong) GTCaptcha4Session *captchaSession;

@implementation ViewController
- (GTCaptcha4Session *)captchaSession {
if (!_captchaSession) {
_captchaSession = [GTCaptcha4Session sessionWithCaptchaID:captchaID];

/// If the default configuration needs to be modified
/// Create an instance by choosing a form annotated below

// GTCaptcha4SessionConfiguration *config = [GTCaptcha4SessionConfiguration
// defaultConfiguration];

// config.timeout = 8.0f;
// ...

// _captchaSession = [GTCaptcha4Session sessionWithCaptchaID:captchaID
// configuration:config];

_captchaSession.delegate = self;

return _captchaSession;

- (void)viewDidLoad {
[super viewDidLoad];

// Initialize captcha session in advance, as if it is not called in this
// location, lazy load mode will be used

[self captchaSession];

[self.startBtn addTarget:self

For other optional configuration items, see the interface or property defined in GTCaptcha4Session.

  1. Call and start CAPTCHA session

Call the following method for verification after initialization is completed:

- (void)start {
[self.captchaSession verify];

Process verification results

This verification is complete only after the verification results are verified.
You need to handle the following proxy methods after complying with the GTCaptcha4Session TaskDelegate protocol:

- (void)gtCaptchaSession:(GTCaptcha4Session *)captchaSession didReceive:(NSString *)code result:(NSDictionary *)result message:(NSString *)message {

NSLog(@"result: %@", result);

// When the code is @"1", it means a successful user authentication; and when it is @"0", it means a failed user authentication

if ([@"1" isEqualToString:code]) {

if (result && result.count > 0) {

// Submit result data to validate

__block NSMutableArray<NSString *> *kvPairs = [NSMutableArray array];

[result enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, id _Nonnull obj, BOOL * _Nonnull stop) {

if ([key isKindOfClass:[NSString class]] &&

[obj isKindOfClass:[NSString class]]) {

NSString *kvPair = [NSString stringWithFormat:@"%@=%@", key, obj];

[kvPairs addObject:kvPair];



NSString *formStr = [kvPairs componentsJoinedByString:@"&"];

NSData *data = [formStr dataUsingEncoding:NSUTF8StringEncoding];

// Verification interface provided by service backend

NSURL *url = [NSURL URLWithString:@"http://xxx.yyy.zzz/path/validate"];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

request.HTTPMethod = @"POST";

request.HTTPBody = data;

// Submit to the back end to verify the results

[[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {

if (!error && data) {

// Process validation results

NSString *msg = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSLog(@"result: %@", msg);


else {

NSLog(@"error: %@", error);


}] resume];




Handle verification errors

Some unexpected errors may occur, which you can handle in the following proxy methods by complying with the GTCaptcha4SessionTaskDelegate protocol:

- (void)gtCaptchaSession:(GTCaptcha4Session *)captchaSession didReceiveError:(GTC4Error *)error {
NSLog(@"error: %@", error.description);

Please refer to the following list for possible error codes: GTC4Error

Swift example

For more example details, please refer to the official Demo, and please refer to the DefaultDemoViewController.swift file in the Demo for Swift example code.

Was this helpful?