如何在设备启动时从 adafruit 获取 MQTT 主题数据

Question

我正在构建一个 iphone 应用程序，它使用 MQTT_Client_Foundation(https://github.com/novastone-media/MQTT-Client-Framework) 订阅和发布 Adafruit.com 上的主题。我让它工作，当服务器上的值更新时它会连接并查找更新，并在点击按钮时发布到服务器。我的问题是我想在打开应用程序时获取服务器上的当前主题值，而不必等待更新。这是我现在的代码：

#import "ViewController.h"
#import <MQTTClient/MQTTClient.h>
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *batteryValueLabel;
@property (strong, nonatomic) IBOutlet UIImageView *tempValueLabel;
@property (strong, nonatomic) IBOutlet UILabel *temperatureValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *levelValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *tripValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *dateValueLabel;
@property(nonatomic, strong, readwrite) NSArray *certificates;
@property(nonatomic, weak) IBOutlet UIButton *Fill;


-(IBAction)Turnon:(id)sender;
@end
NSString *trip = @"0";
int trigger =1;
int B = 50;
int T = 90;
MQTTSession *session;
@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.tempValueLabel.frame = CGRectMake(20, 250-(T+45),65, T+45);
    _batteryValueLabel.frame = CGRectMake(114, 287, B*1.7, 63);
    NSString* myNewString = [NSString stringWithFormat:@"%d", T];
    self.temperatureValueLabel.text = myNewString;
    MQTTCFSocketTransport *transport = [[MQTTCFSocketTransport alloc] init];
    transport.host = @"io.adafruit.com";
    transport.port = 1883;
   
    session = [[MQTTSession alloc] init];
    session.userName = @"xxxxxxxxx";
    session.password = @"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
    session.transport = transport;
    session.delegate = self;

//此处为 /GET

修改的代码

     [session connectWithConnectHandler:^(NSError *error) {
   
        if(!error){
            
            [session subscribeToTopic:@"XXXXXX/feeds/+" atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){
                
        if (error) {
            NSLog(@"Subscription failed %@", error.localizedDescription);
        } else {
            NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss);
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

//在我看来他们传递的是数字而不是字符串

            trip = @"0";
            NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
            [session publishData:data onTopic:@"gbenna/feeds/temperature/get" retain:NO qos:1 publishHandler:nil];
            NSLog(@"%@", trip);
            NSLog(@"%d",trigger);
                });}
    }];
            }
        else {NSLog(@"[connectWithConnectHandler]Error Connect %@", error.localizedDescription);}
    
    
}];

}

//this is continuously called and gets data when server values are updated
- (void)newMessage:(MQTTSession *)session
              data:(NSData *)data
           onTopic:(NSString *)topic
               qos:(MQTTQosLevel)qos
          retained:(BOOL)retained
               mid:(unsigned int)mid {
    NSString *dataString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"topic: %@", topic);
    NSLog(@"data:%@", dataString);
    if ([topic isEqualToString:@"xxxxxxx/feeds/temperature"]){
        T = [dataString intValue];
        self.temperatureValueLabel.text = dataString;
        self.tempValueLabel.frame = CGRectMake(20, 250-(T+45),65, T+45);
        if (T <= 69) {
            _tempValueLabel.image = [UIImage imageNamed:@"dk blue rectangle.png"];
        }
        else if ((69< B)&& (B <= 90)) {
            _tempValueLabel.image = [UIImage imageNamed:@"blue rectangle.png"];
        }
        else if (B > 90) {
            _tempValueLabel.image = [UIImage imageNamed:@"red rectangle.png"];
        }
    }
    if ([topic isEqualToString:@"xxxxxxxx/feeds/level"]){
        self.levelValueLabel.text = dataString;}
    if ([topic isEqualToString:@"xxxxxxxx/feeds/date"]){
        self.dateValueLabel.text = dataString;}
    if ([topic isEqualToString:@"xxxxxxxx/feeds/battery"]){
      
        B = [dataString intValue];
        _batteryValueLabel.frame = CGRectMake(114, 287, B*1.7, 63);
        if (B <= 20) {
            _batteryValueLabel.image = [UIImage imageNamed:@"red rectangle.png"];
        }
        else if ((20< B)&& (B <= 100)) {
            _batteryValueLabel.image = [UIImage imageNamed:@"green rectangle.png"];
        }
        else if (B > 100) {
            _batteryValueLabel.image = [UIImage imageNamed:@"red rectangle.png"];
        }
    }
    if ([topic isEqualToString:@"xxxxxxxxx/feeds/trip"]){
        self.tripValueLabel.text = dataString;}


}
//when I tap this button the value on the server is updated
-(IBAction)Turnon:(id)sender;{
    if(trigger ==1){
        trip = @"0";
        trigger = 2;
    }
    else if(trigger==2){
        trip = @"100";
        trigger = 1;
    }
    NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
    [session publishData:data onTopic:@"xxxxxxxxx/feeds/trip" retain:NO qos:1 publishHandler:nil];
    NSLog(@"%@", trip);
    NSLog(@"%d",trigger);
}
@end

有谁知道什么代码以及把它放在哪里，这样当我打开应用程序时它就可以在服务器上获取当前主题值而无需等待更新？

Answer 1

我成功了这是我的代码

#import "ViewController.h"
#import <MQTTClient/MQTTClient.h>
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *batteryValueLabel;
@property (strong, nonatomic) IBOutlet UIImageView *tempValueLabel;
@property (strong, nonatomic) IBOutlet UILabel *temperatureValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *levelValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *tripValueLabel;
@property (weak, nonatomic) IBOutlet UILabel *dateValueLabel;
@property(nonatomic, strong, readwrite) NSArray *certificates;
@property(nonatomic, weak) IBOutlet UIButton *Fill;


-(IBAction)Turnon:(id)sender;
-(IBAction)update:(id)sender;
@end
NSString *trip = @"0";
int trigger =1;
int B = 50;
int T = 90;
MQTTSession *session;
@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.tempValueLabel.frame = CGRectMake(20, 250-(T+45),65, T+45);
    
    NSString* myNewString = [NSString stringWithFormat:@"%d", T];
    self.temperatureValueLabel.text = myNewString;
    MQTTCFSocketTransport *transport = [[MQTTCFSocketTransport alloc] init];
    transport.host = @"io.adafruit.com";
    transport.port = 1883;
    session = [[MQTTSession alloc] init];
    session.userName = @"xxxxxxxx";
    session.password = @"xxxxxxxxxxxxxxxxxxx";
    session.transport = transport;
    session.delegate = self;
    [session connectWithConnectHandler:^(NSError *error) {
            if(!error){
                
                [session subscribeToTopic:@"xxxxxxxx/feeds/temperature" atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){
                    
            if (error) {
                NSLog(@"Subscription failed %@", error.localizedDescription);
            } else {
                NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss);
                
                trip = @"0";
                NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
                [session publishData:data onTopic:@"gbenna/feeds/temperature/get" retain:NO qos:0 publishHandler:nil];
                NSLog(@"%@", trip);
                NSLog(@"%d",trigger);
                   }
        }];
                [session subscribeToTopic:@"xxxxxxx/feeds/battery" atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){
                    
            if (error) {
                NSLog(@"Subscription failed %@", error.localizedDescription);
            } else {
                NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss);
                
                trip = @"0";
                NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
                [session publishData:data onTopic:@"xxxxxxx/feeds/battery/get" retain:NO qos:0 publishHandler:nil];
                NSLog(@"%@", trip);
                NSLog(@"%d",trigger);
                    }
        }];
                [session subscribeToTopic:@"xxxxxxxx/feeds/level" atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){
                    
            if (error) {
                NSLog(@"Subscription failed %@", error.localizedDescription);
            } else {
                NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss);
                
                trip = @"0";
                NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
                [session publishData:data onTopic:@"xxxxxxx/feeds/level/get" retain:NO qos:0 publishHandler:nil];
                NSLog(@"%@", trip);
                NSLog(@"%d",trigger);
                    }
        }];
                [session subscribeToTopic:@"gbenna/feeds/date" atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){
            
            if (error) {
                NSLog(@"Subscription failed %@", error.localizedDescription);
            } else {
                NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss);
                
                trip = @"0";
                NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
                [session publishData:data onTopic:@"xxxxxxx/feeds/date/get" retain:NO qos:0 publishHandler:nil];
                NSLog(@"%@", trip);
                NSLog(@"%d",trigger);
                   }
        }];
                [session subscribeToTopic:@"xxxxxxx/feeds/trip" atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){
            
            if (error) {
                NSLog(@"Subscription failed %@", error.localizedDescription);
            } else {
                NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss);
                
                trip = @"0";
                NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
                [session publishData:data onTopic:@"xxxxxxx/feeds/trip/get" retain:NO qos:0 publishHandler:nil];
                NSLog(@"%@", trip);
                NSLog(@"%d",trigger);
                   }
        }];
                }
            else {NSLog(@"[connectWithConnectHandler]Error Connect %@", error.localizedDescription);}
        
        
    }];
   
  
    
    
}

- (void)newMessage:(MQTTSession *)session
              data:(NSData *)data
           onTopic:(NSString *)topic
               qos:(MQTTQosLevel)qos
          retained:(BOOL)retained
               mid:(unsigned int)mid {
    NSString *dataString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"topic: %@", topic);
    NSLog(@"data:%@", dataString);
    if ([topic isEqualToString:@"xxxxxx/feeds/temperature"]){
        T = [dataString intValue];
        self.temperatureValueLabel.text = dataString;
        self.tempValueLabel.frame = CGRectMake(20, 250-(T+45),65, T+45);
        if (T <= 69) {
            _tempValueLabel.image = [UIImage imageNamed:@"dk blue rectangle.png"];
        }
        else if ((69< B)&& (B <= 90)) {
            _tempValueLabel.image = [UIImage imageNamed:@"blue rectangle.png"];
        }
        else if (B > 90) {
            _tempValueLabel.image = [UIImage imageNamed:@"red rectangle.png"];
        }
    }
    if ([topic isEqualToString:@"xxxxxx/feeds/level"]){
        self.levelValueLabel.text = dataString;}
    if ([topic isEqualToString:@"xxxxxx/feeds/date"]){
        self.dateValueLabel.text = dataString;}
    if ([topic isEqualToString:@"xxxxxxx/feeds/battery"]){
      
        B = [dataString intValue];
        self.batteryValueLabel.frame = CGRectMake(332, 250-(B*1.7), 65, B);
        if (B <= 20) {
            _batteryValueLabel.image = [UIImage imageNamed:@"red rectangle.png"];
        }
        else if ((20< B)&& (B <= 100)) {
            _batteryValueLabel.image = [UIImage imageNamed:@"green rectangle.png"];
        }
        else if (B > 100) {
            _batteryValueLabel.image = [UIImage imageNamed:@"red rectangle.png"];
        }
    }
    if ([topic isEqualToString:@"xxxxxxx/feeds/trip"]){
        self.tripValueLabel.text = dataString;}


}
-(IBAction)Turnon:(id)sender;{
    if(trigger ==1){
        trip = @"0";
        trigger = 2;
    }
    else if(trigger==2){
        trip = @"100";
        trigger = 1;
    }
    NSData* data = [trip dataUsingEncoding:NSUTF8StringEncoding];
    [session publishData:data onTopic:@"xxxxxxx/feeds/trip" retain:NO qos:1 publishHandler:nil];
    NSLog(@"%@", trip);
    NSLog(@"%d",trigger);
    
}

@end

连接到服务器后，我订阅了一个主题，然后当我订阅了该主题时，我发布了它的 /get 方法。我为每个主题都这样做了。当我启动我的应用程序时，它们都会更新每个主题的最新当前值。我将尝试看看当我回到后台时会发生什么，也许还会添加一个按钮来更新（/获取）所有主题。

感谢大家的帮助。

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