iOS支付宝微信h5支付无法返回App解决方案

由于app购买的是虚拟商品，原生接入支付宝微信支付会有苹果审核风险，故采用h5接入支付。

存在的问题：

• 微信支付成功无法返回app，而是打开了Safari
• 支付宝支付成功还是停留在了支付宝

1.微信支付

1. 微信后台配置授权域名，如 http: //aaa.bbb.com
2. 在App工程配置中添加 URL Schemes: aaa.bbb.com （必须与域名保持一致）
3. 拦截WKWebView代理方法

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {

    NSURL *url = navigationAction.request.URL;
    if ([url.absoluteString hasPrefix:@"weixin://"]) {
        if ([[UIApplication sharedApplication] canOpenURL:url]) {
            [[UIApplication sharedApplication] openURL:url];
        }
    }
    NSString *kWXPay_url = @"https://wx.tenpay.com/cgi-bin/mmpayweb-bin/checkmweb"; //微信下单url
    NSString *referer = @"aaa.bbb.com://"; //与scheme、微信配置的授权域名 保持一致
    
    if ([url.absoluteString containsString:kWXPay_url]) {
        NSDictionary *headers = [navigationAction.request allHTTPHeaderFields];
        BOOL hasReferer = [referer isEqualToString:[headers objectForKey:@"Referer"]];
        if (hasReferer) { //已经设置了
            decisionHandler(WKNavigationActionPolicyAllow);
        } else {
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
                dispatch_async(dispatch_get_main_queue(), ^{
                    NSURL *url = [navigationAction.request URL];
                    NSMutableDictionary *dic = [[url bf_queryDictionary] mutableCopy];
                    if ([dic.allKeys containsObject:@"redirect_url"]) {
                        self.redirect_url = dic[@"redirect_url"]; //保存redirect_url,用于刷新支付结果
                        [dic removeObjectForKey:@"redirect_url"]; //去掉参数里的redirect_url,否则会回到safari
                    }
                    NSString *urlStr = [NSString stringWithFormat:@"%@?prepay_id=%@&package=%@",kWXPay_url,dic[@"prepay_id"],dic[@"package"]];
                    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:urlStr] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:20.0];
                    [request setHTTPMethod:@"GET"];
                    [request setValue:referer forHTTPHeaderField: @"Referer"];
                    [self.webView loadRequest:request];
                });
            });
            decisionHandler(WKNavigationActionPolicyCancel);
        }
        return;
    }
    decisionHandler(WKNavigationActionPolicyAllow);
}

//监听app回到前台事件
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleWillEnterForeground) name:UIApplicationWillEnterForegroundNotification object:nil];

- (void)handleWillEnterForeground {
    if (self.redirect_url) {
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:self.redirect_url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:20.0];
    [self.webView loadRequest:request];
        self.redirect_url = nil;
    }
}

//记得移除监听
- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}
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说明：

• 拦截跳转微信的url，用 [[UIApplication sharedApplication] openURL:url] 打开，才会跳转微信客户端
• 拦截微信下单地址 kWXPay_url，设置请求头的 Referer ，格式为 scheme://
• 去掉url参数里的回调地址redirect_url，否则支付成功还是会打开Safari。同时保存redirect_url地址，当支付成功时监听app回到前台的事件，刷新webView更新支付状态。

2.支付宝

支付宝相对于微信要简单的多，只需要拦截跳转支付宝的url，将 fromAppUrlScheme 替换为自己的scheme（如aaa），再用 [[UIApplication sharedApplication] openURL:url] 打开即可。
（后端和h5都说fromAppUrlScheme的值他们改不了，所以由客户端拦截替换）

- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    NSURL *url = navigationAction.request.URL;
    if ([url.absoluteString hasPrefix:@"alipay://"] ||
        [url.absoluteString hasPrefix:@"alipays://"]) {
        
        //替换scheme为aaa
        NSString *newUrl = [url.absoluteString stringByReplacingOccurrencesOfString:@"fromAppUrlScheme%22%3A%22alipays" withString:@"fromAppUrlScheme%22%3A%22aaa"];
        if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:newUrl]]) {
            [[UIApplication sharedApplication] openURL:[NSURL URLWithString:newUrl]];
        }
    }
    decisionHandler(WKNavigationActionPolicyAllow);
 }
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