The Stripe iOS bindings make it easy to collect your users' credit card details inside your iOS app. By creating tokens, Stripe handles the bulk of PCI compliance by preventing sensitive card data from hitting your server (for more, see our article about PCI compliance).
To get started, see our tutorial.
There are two ways to add Stripe to your project:
CocoaPods is a common library dependency management tool for Objective-C. To use the Stripe iOS bindings with CocoaPods, simply add the following to your Podfile and run pod install:
pod 'Stripe', :git => 'https://github.com/stripe/stripe-ios.git'
Note: be sure to use the .xcworkspace to open your project in Xcode instead of the .xcproject. You will also need to add the QuartzCore framework to your project.
- Clone this repository (
git clone --recursive) - In the menubar, click on 'File' then 'Add files to "Project"...'
- Select the 'Stripe' directory in your cloned stripe-ios repository
- Make sure "Copy items into destination group's folder (if needed)" is checked"
- Click "Add"
You will also need to add the QuartzCore framework to your project.
You can also clone this repository to see our example app, TreatCar. To do so, just clone this repository, then initialize submodules:
git submodule update --init --recursive
Then, simply open Stripe.xcodeproj in Xcode and run TreatCar.
First, you need to create a view to collect your users' card details. We've created the STPView class which does this all for you, or you can create a custom view of your own.
Create and show a STPView:
STPView *cardView = [[STPView alloc] initWithFrame:CGRectMake(15,20,290,55) andKey:@"my_publishable_key"];
[self.view addSubview:cardView];
To receive feedback about the state of the view:
cardView.delegate = self // implement STPViewDelegate
...
- (void)stripeView:(STPView *)view withCard:(PKCard *)card isValid:(BOOL)valid
{
// Enable the "save" button only if the card form is complete.
self.navigationItem.rightBarButtonItem.enabled = valid;
}
Finally, submit the details to Stripe to receive a token:
[cardView createToken:^(STPToken *token, NSError *error) {
if (error) {
[self hasError:error];
} else {
[self hasToken:token]; // Hooray!
}
}];
(Replace @"my_publishable_key" with your publishable key.)
After showing your view, create and populate a STPCard with the details you collected:
STPCard *card = [[STPCard alloc] init];
card.number = @"4242424242424242";
card.expMonth = 12;
card.expYear = 2020;
Then send it to Stripe:
[Stripe createTokenWithCard:card
publishableKey:@"my_publishable_key"
completion:^(STPToken *token, NSError *error) {
if (error) {
[self hasError:error];
} else {
[self hasToken:token]; // Hooray!
}
}];
(Replace @"my_publishable_key" with your publishable key.)
Once you've collected a token, you can send it to your server to charge immediately or create a customer to charge in the future.
These operations need to occur in your server-side code (not the iOS bindings) since these operations require your secret key.
If you do not wish to send your publishableKey every time you make a call to createTokenWithCard, you can also call [Stripe setDefaultPublishableKey:] with your publishable key. All Stripe subsequent API requests will use this key.
If you're implementing a complex workflow, you may want to know if you've already charged a token (since they can only be charged once). You can do so if you have the token's ID:
[Stripe getTokenWithId:@"token_id"
publishableKey:@"my_publishable_key"
completion:^(STPToken *token, NSError *error)
{
if (error)
NSLog(@"An error!");
else
NSLog(@"A token for my troubles.");
}];
Expected errors, such as a card being invalid, generate NSError objects. The bindings will return errors that are in the StripeDomain domain and have a code of STPInvalidRequestError, STPAPIError, or STPCardError -- these match up to the type property of errors returned by the Stripe API. Additionally, as recommended by Cocoa guidelines, all errors in the StripeDomain also provide a localizable user-facing error message that can be retrieved by calling [error localizedDescription].
The userInfo dictionary of errors in the StripeDomain contains a developer-facing error message corresponding to the message property returned by the Stripe API for an error, and, when applicable, a card error code corresponding to the code property and a parameter the error is for corresponding to the param property. These are the values for the keys STPErrorMessageKey, STPCardErrorCodeKey, and STPErrorParameterKey in the userInfo dictionary, respectively. Note that the values for STPErrorParameterKey will be camel cased and match up to the properties on STPCard. For example, an invalid expiration month will have expMonth, not exp_month, as the value for STPErrorParameterKey in the userInfo dictionary).
Almost all calls made to methods in the Stripe iOS bindings return nothing but errors in the StripeDomain. The only exception to this is calls to createTokenWithCard and getTokenWithId. Both of these methods make requests using NSURLConnection, so if the request fails to even be made, these calls just return the error object that is generated and returned by NSURLConnection (which will be in the NSURLErrorDomain).
When you are writing an iOS application, it is important to keep the main thread responsive even if your application performs a time-consuming task. In most cases, you should be able to use the default createToken and getToken methods for creating and retrieving tokens, which will run your completionHandler block on [NSOperationQueue mainQueue]. However, if you have a more complicated application and want to control where your completionHandler gets run, you can also pass in a queue as a parameter to both of these calls. See:
+ (void)createTokenWithCard:publishableKey:operationQueue:completionHandler
+ (void)getTokenWithId:publishableKey:operationQueue:completionHandler
You have a few options for handling validation of credit card data on the client, depending on what your application does. Client-side validation of credit card data is not required since our API will correctly reject invalid card information, but can be useful to validate information as soon as a user enters it, or simply to save a network request.
The simplest thing you can do is to populate your STPCard object and, before sending the request, call - (BOOL)validateCardReturningError: on the card. This validates the entire card object, but is not useful for validating card properties one at a time.
To validate STPCard properties individually, you should use the following:
- (BOOL)validateNumber:error:
- (BOOL)validateCvc:error:
- (BOOL)validateExpMonth:error:
- (BOOL)validateExpYear:error:
These methods follow the validation method convention used by key-value validation. So, you can use these methods by invoking them directly, or by calling [card validateValue:forKey:error] for a property on the STPCard object.
When using these validation methods, you will want to set the property on your card object when a property does validate before validating the next property. This allows the methods to use existing properties on the card correctly to validate a new property. For example, validating 5 for the expMonth property will return YES if no expYear is set. But if expYear is set and you try to set expMonth to 5 and the combination of expMonth and expYear is in the past, 5 will not validate. The order in which you call the validate methods does not matter for this though.
- Open Stripe.xcodeproj
- Select either the iOS or OS X scheme in the toolbar at the top
- Go to Product->Test
OS X support is not yet well tested (though all the tests do run). Feel free to give it a try and let us know of any problems you run into!