WeChat Pay

Development Procedure on the App

Key Development Points for iOS

For example, to develop an app in Xcode6.0 and run it in IOS7.0, take the following steps:

1. Set APPID

After a merchant applies for development of an app on WeChat Open Platform, a unique APPID is generated for the app. Open the project in Xcode and set URL Schemes in the project property to your APPID, As shown in the red position in Fig. 8.7.

Fig.8.7

2. Register APPID

WeChat lib library and head file are introduced in the merchant app project. Before calling the API, you need to register your APPID with WeChat. The code is as follows:

[WXApi registerApp:@"wxd930ea5d5a258f4f" withDescription:@"demo 2.0"];

3. Call payment

To generate a payment order, the merchant server first calls the [Order Placement API] to generate a prepayment order, and signs the obtained parameter prepay_id again before transferring it to the app to initiate payment. The key code to call WeChat Pay is as follows:

PayReq *request = [[[PayReq alloc] init] autorelease];
request.partnerId = @"10000100";
request.prepayId= @"1101000000140415649af9fc314aa427";
request.package = @"Sign=WXPay";
request.nonceStr= @"a462b76e7436e98e0ed6e13c64b4fd1c";
request.timeStamp= @"1397527777";
request.sign= @"582282d72dd2b03ad892830965f428cb16e7a256";
[WXApi safeSendReq:request];

4. Payment result callback

Payment result callback

- (void)onResp:(BaseResp *)resp {
    if ([resp isKindOfClass:[PayResp class]]) {
        PayResp *response = (PayResp *)resp;
        switch (response.errCode) {
            case WXSuccess:
     	    		//Prompt of successful payment according to server-based query result or API returned data
     	     		NSlog(@"Payment Successful");
            	break;
        	 default: 
           	NSlog(@"Payment Failed， retcode=%d",resp.errCode);
            	break;
            }
	}
}

List of errCode values in callback:

Key Development Points for Android

1. Backend settings

After a merchant applies for development of an app on WeChat Open Platform, a unique APPID is generated for the app. To ensure payment security, the package name and the signature of the merchant app must be bound on WeChat Open Platform before making payments. "Settings" can be found under "Admin Console" > "Change App" > "Change Development Information" in "WeChat Open Platform", as shown in the red box of Fig. 8.8.

Fig. 8.8

App package name: The package value declared in the app configuration file AndroidManifest.xml, such as package="net.sourceforge.simcpux" in DEMO.

App signature: According to the app package name and keystore used for project compilation, you can generate a 32-digit md5 string using the signature tool installed on the debugging mobile. Run the tool to generate an app signature string. As shown in Fig. 8.9, the green string is the app signature. Signature tool download address: https://open.weixin.qq.com/zh_CN/htmledition/res/dev/download/sdk/Gen_Signature_Android.apk

Fig. 8.9

2. Register APPID

WeChat JAR package is introduced in the merchant app project. Before calling the API, you need to register your APPID with WeChat. The code is as follows:

final IWXAPI msgApi = WXAPIFactory.createWXAPI(context, null);
// Register this app with WeChat 
msgApi.registerApp("wxd930ea5d5a258f4f");

3. Call payment

To generate a payment order, the merchant server first calls the unified order placement API (see Section 7) to generate a prepayment order, and then signs the obtained parameter prepay_id again before transferring it to the app to initiate payment. The key code to call WeChat Pay is as follows:

IWXAPI api;
PayReq request = new PayReq();
request.appId = "wxd930ea5d5a258f4f";
request.partnerId = "1900000109";
request.prepayId= "1101000000140415649af9fc314aa427",;
request.packageValue = "Sign=WXPay";
request.nonceStr= "1101000000140429eb40476f8896f4c9";
request.timeStamp= "1398746574";
request.sign= "7FFECB600D7157C5AA49810D2D8F28BC2811827B";
api.sendReq(request);

4. Payment result callbak

According to the WeChat SDK Sample, implement the WXPayEntryActivity class in the path of the package net.sourceforge.simcpux.wxapi (inconsistent package name or class name will result in callback failure) and the onResp function in the WXPayEntryActivity class. After the payment is completed, the WeChat app will return to the merchant app and call back the onResp function. The developer needs to receive notification in this function and determine the returned error code. In case of a successful payment, the developer needs to query the payment result at the console and display the actual result of payment made by the user. Note that the result returned by the client must not be considered as the user's payment result. The payment notification received by the server or the result returned via the query API should prevail. The sample code is as follows:

public void onResp(BaseResp resp) {
	if (resp.getType() == ConstantsAPI.COMMAND_PAY_BY_WX) {
		Log.d(TAG, "onPayFinish, errCode = " + resp.errCode);
		AlertDialog.Builder builder = new AlertDialog.Builder(this);
		builder.setTitle(R.string.app_tip);
	}
}

List of errCode values in callback: