First, download the SDK from wechat Developer Platform at:

https://open.weixin.qq.com/cgi-bin/showdocumentaction=dir_list&t=resource/res_list&verify=1&id=open1419319164&lang=zh_CN

Add LSApplicationQueriesSchemes array in plist file, add two strings for calling wechat

Import dependency library SystemConfiguration.framework, libz.dylib, libsqlite3.0.dylib, libc++.dylib, Security.framework, CoreTelephony.framework, CFNetwork.framework

Add white list

Select Build Setting in your project file, and add "- ObjC and - all_load" in "Other Linker Flags"

Follow protocol and add header file in Appdelegate.h

#import "AppDelegate.h"
#import "WXApi.h"

@interface AppDelegate ()<WXApiDelegate>

@end

Register wechat Wx? appId in the didFinishLaunchingWithOptions method in Appdelegate.m is the appId on your wechat Developer Platform

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    // Wechat registration
    [WXApi registerApp:WX_AppId];
    return YES;
}

Add proxy method in Appdelegate.m

// This method is used to return the third-party App from wechat
- (BOOL)application:(UIApplication *)app openURL:(NSURL *)url options:(NSDictionary<NSString*,id> *)options NS_AVAILABLE_IOS(9_0){
    
    [WXApi handleOpenURL:url delegate:self];
    
    return YES;
}

Callback method in Appdelegate.m

[self.window showmbhudallertwithmessage: @ "wechat authorization failed" hide:1.0]; it is a prompt box

- (void)onResp:(BaseResp *)resp{
    
    // ===============Wechat login authorization callback obtained============
    if ([resp isMemberOfClass:[SendAuthResp class]])  {
        NSLog(@"******************Wechat login authorization obtained******************");
        
        SendAuthResp *aresp = (SendAuthResp *)resp;
        if (aresp.errCode != 0 ) {
            dispatch_async(dispatch_get_main_queue(), ^{
                [self.window showMBHUDAlertWithMessage:@"Wechat authorization failed" hide:1.0];
            });
            return;
        }
        
        NSString *code = aresp.code;
        [self getWeiXinOpenId:code];
    }
}

Get token and openid in AppDelegate.m

//access_token, openid, unionid through code
- (void)getWeiXinOpenId:(NSString *)code{
    NSString *url =[NSString stringWithFormat:@"https://api.weixin.qq.com/sns/oauth2/access_token?appid=%@&secret=%@&code=%@&grant_type=authorization_code",WX_AppId,WX_AppSerect,code];
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSURL *zoneUrl = [NSURL URLWithString:url];
        NSString *zoneStr = [NSString stringWithContentsOfURL:zoneUrl encoding:NSUTF8StringEncoding error:nil];
        NSData *data1 = [zoneStr dataUsingEncoding:NSUTF8StringEncoding];
        
        if (!data1) {
            [self.window showMBHUDAlertWithMessage:@"Wechat authorization failed" hide:1.0];
            return ;
        }
        
        // Authorization succeeded, get token and openID dictionary
        NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data1 options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"token,openID Dictionaries===%@",dic);
        self.access_token = dic[@"access_token"];
        self.openid= dic[@"openid"];
        
        //         Get wechat user information
        [self getUserInfo];
        
    });
}

Appdelete. M user obtains wechat user information

-(void)getUserInfo
{
    NSString *url =[NSString stringWithFormat:@"https://api.weixin.qq.com/sns/userinfo?access_token=%@&openid=%@",self.access_token,self.openid];
    
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSURL *zoneUrl = [NSURL URLWithString:url];
        NSString *zoneStr = [NSString stringWithContentsOfURL:zoneUrl encoding:NSUTF8StringEncoding error:nil];
        NSData *data = [zoneStr dataUsingEncoding:NSUTF8StringEncoding];
        dispatch_async(dispatch_get_main_queue(), ^{
            
            // Failed to get user information
            if (!data) {
                [self.window showMBHUDAlertWithMessage:@"Wechat authorization failed" hide:1.0];
                return ;
            }
            
            // Get user information dictionary
            NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
            NSLog(@"User information dictionary:===%@",dic);
            
        });
        
    });
}

Write in wechat login event

if ([WXApi isWXAppInstalled]) {
        
        //Construct SendAuthReq structure
        SendAuthReq *req = [[SendAuthReq alloc] init];
        req.scope = @"snsapi_userinfo";
        req.state = @"App";
        //Send a SendAuthReq message structure to the wechat terminal
        [WXApi sendReq:req];
    }else{
        
        UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"reminder" message:@"Please install wechat client first" preferredStyle:UIAlertControllerStyleAlert];
        UIAlertAction *action = [UIAlertAction actionWithTitle:@"determine" style:UIAlertActionStyleDefault handler:nil];
        [alert addAction:action];
        [self presentViewController:alert animated:YES completion:nil];
    }

End!!!