How to call Objective-C functions using JavaScript on iOS/Mac
In Cocos2d-JS v3.0 RC2, we'd like to introduce you the js to Objective-C reflection feature. Like we can call native functions on Java by JS, you can now invoke Objective-C Static Method in JS too.
var ojb = jsb.reflection.callStaticMethod(className, methodNmae, arg1, arg2, .....);
You can use jsb.reflection.callStaticMethod
to call Native OC method by sending className
methodName
and parameters
.
Notice: Please pay attention to Apple Developer Program License Agreement (section 3.3.2) when you use reflection features. The usage of respondsToSelector:
and performSelector:
might cause problem in App Store review process, here is a related discussion in React-Native's issue tracker.
Objective-C Class
- You will need to provide your functionality in an OC class as the example below, the
className
parameter in this case should beNativeOcClass
.
import <Foundation/Foundation.h>
@interface NativeOcClass : NSObject
+(BOOL)callNativeUIWithTitle:(NSString *)title andContent:(NSString *)content;
@end
Objective-C Method
The reflection from js to OC support only static method of an OC class.
methodName
parameter in previous example is the OC method name in your class, takeNativeOcClass
as an example, we can see a method named+(BOOL)callNativeUIWithTitle:(NSString *)title andContent:(NSString *)content;
So the
methodName
should becallNativeUIWithTitle:addContent:
which is the definition for this method, and don't forget the :. We cannot discuss the details here, but if you are interested, you can search for Objective-C programming guide for more details.Another example below, the
methodName
should becallNativeWithReturnString
.
+(NSString *)callNativeWithReturnString;
Useage
- In JS code, for invoking the native method
callNativeUIWithTitle:andContent:
ofNativeOcClass
, we can usejsb.reflection.callStaticMethod
API like this:
var ret = jsb.reflection.callStaticMethod("NativeOcClass",
"callNativeUIWithTitle:andContent:",
"cocos2d-js",
"Yes! you call a Native UI from Reflection");
- This method can show an alert dialog and return a boolean status. Here is its implementation,
title
andcontent
parameters will receive the strings you sent from js:
+(BOOL)callNativeUIWithTitle:(NSString *) title andContent:(NSString *)content{
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title message:content delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"OK", nil];
[alertView show];
return true;
}
Notice
Types supported for parameters and return value are limited in Cocos2d-JS reflection.
- If you need to use float, int, double as parameter types in your native method, you need to change to use
NSNumber
instead. - If you need to use bool as parameter type, you need to change to use
BOOL
instead. - Here is an example, we use
NSNumber
instead of int, float or double.
+(float) addTwoNumber:(NSNumber *)num1 and:(NSNumber *)num2 {
float result = [num1 floatValue] + [num2 floatValue];
return result;
}
- For return value we only support int, float, bool, string in the current version.