Javascript Examples

http://support.rollout.io/docs/javascript-examples

This document contain examples on how JavaScript can be used, here is a quick list of examples we have

Example	Desctiption
Show alert to a user when an exception happens	call original function, catch exception and alert to user if exception got caught
Redirect to another function	Instead of running original method call a different method
Create a new instance	Call an alloc init to create a new instance
Call a method on an instance	Calling a method on an instance and supplying them arguments

Show Alert in case of Exception

---

call the original method and catch the exception, in case the exception is caught pop an alert to the user
Patched method

Objective-C

-(int) runSomethingAndReturnIndex;

Problem
method crash with NSException from time to time
Solution
Surround the function with try catch and return -1 instead

JavaScript

try {  returnValue = R.beta.originalImplementation();//calls the original implementation }catch (e) {  returnValue = -1;} return returnValue;};

Redirect method

---

Redirect invocation to a different method with different args
Patched method

Objective-C

-(NSString*) doA;

Redirected method

Objective-C

-(NSString*) doBWith:(NSString*) prefix;

Problem
We would like to redirect the call from doA to doB: and supply doB`` an empty string for it'sprefix``` argument

JavaScript

Examples['-']['doA'] = function ( ) {  var returnValue; // JSBox<NSString *>  // write area starts here  returnValue =  R.beta.callMethod(self, "doBWith:", "");  // write area ends here  return returnValue;};

Create a new instance

---

Create a class instance and call alloc init to create a new instance
Init method 

Objective-C

@interface Person: NSObject  -(instancetype) initWithName: (NSString*) name age:(int) age;@end

Javascript code 

JavaScript

var PersonClass = R.beta.NSClassFromString("Person");// create a class of Personvar person = R.beta.callMethod(R.beta.callMethod(PersonClass, "alloc"), "initWithName:age:", "Arthur Dent", 42); // call alloc and initWithName:age:

Call method on instance

---

Calling a method on an instance and supplying them arguments

Target method 
For this example we created a method that accepts a bunch or argument from different types to demonstrate how the arguments are passed 

Objective-C

@interface Examples: NSObject-(void) doSomethingWithPerson:(Person*) p string:(NSString*) s dictionary:(NSDictionary*) dict double:(double) d integer:(int);@end

Beside Person* argument all other arguments are convertible from JSBox to JavaScript value (see Javascript Docs)
to create JSBox<Examples> or JSBox<Person> take a look at create a new instance example

JavaScript

// assuming person instance already available from type JSBox<Person>// assuming exmaple instance already available from type JSBox<Examples>R.beta.callMethod(example, "doSomethingWithPerson:string:dictionary:double:integer:", person, "hi", {key:"value"}, 10.423, 2);

Open URL

---

opens a url on device

JavaScript

var UIApplicationClass = R.beta.NSClassFromString('UIApplication');var sharedInstance = R.beta.callMethod(UIApplicationClass, 'sharedApplication'); var NSUrlClass = R.beta.NSClassFromString('NSURL');var url = R.beta.callMethod(NSUrlClass, 'URLWithString:', 'http://www.asciimation.co.nz/');R.beta.callMethod(sharedInstance, 'openURL:', url);

Replace http with https

---

For a given NSURL generate a new NSURL with a different string (replace http with https in this example) 

JavaScript

// httpNSURL is from JSBox<NSURL>var httpUrlStringBoxType = R.beta.callMethod(httpNSURL, 'valueForKeyPath:', 'absoluteString'); // from type JSBox<NSString>var httpUrlString = httpUrlStringBoxType.toJS(); // convert to JavaScript string valuevar httpsUrlString = httpUrlString.replace(/^http:/, 'https:'); var httpsNSURL = R.beta.callMethod(R.beta.callMethod(R.beta.NSClassFromString('NSURL'), 'alloc'), 'initWithString:', httpsUrlString); // generate class NSURL -> call alloc on class -> call initWithString: on instancehttpNSURL  = httpsNSURL;// replace the original httpNSURL

Crittercism Add Breadcrumb

---

Code in Objective C

Objective-C

[Crittercism leaveBreadcrumb:@"User tapped start button"];

Code in JavaScript

JavaScript

var CrittercismClass = R.beta.NSClassFromString("Crittercism"); // create a class of CrittercismR.beta.callMethod(CrittercismClass,"leaveBreadcrumb:", "User tapped start button");