Question

怎么将消息发送到mqtt代理服务器

Answer 1

通过Cocoa Pods添加MQTTKit

MQTTKit在github上链接https://github.com/NormanLeeIOS/MQTTKit#send-a-message，down下来。

cd到工程目录，输入pod install，用xcode打开工程的打开xcworkspace扩展名的文件。

如果不是MQTTKit存在更新的版本，则输入pod update。

新建一个MQTT的服务请求

NSString *clientID = ...
MQTTClient *client = [[MQTTClient alloc] initWithClientId:clientID];

发送消息，每次发送消息包括目标host和本地MQTT消息.具体MQTT格式消息见代码。这里Host可以是Server的IP，不需要host表解析。

// connect to the MQTT server
[self.client connectToHost:@"iot.eclipse.org"
completionHandler:^(NSUInteger code) {
if (code == ConnectionAccepted) {
// when the client is connected, send a MQTT message
[self.client publishString:@"Hello, MQTT"
toTopic:@"/MQTTKit/example"
withQos:AtMostOnce
retain:NO
completionHandler:^(int mid) {
NSLog(@"message has been delivered");
}];
}
}];

订阅主题并接受MQTT格式的消息，这部分在viewdidload中实现。

// define the handler that will be called when MQTT messages are received by the client
[self.client setMessageHandler:^(MQTTMessage *message) {
NSString *text = [message.payloadString];
NSLog(@"received message %@", text);
}];

// connect the MQTT client
[self.client connectToHost:@"iot.eclipse.org"
completionHandler:^(MQTTConnectionReturnCode code) {
if (code == ConnectionAccepted) {
// when the client is connected, subscribe to the topic to receive message.
[self.client subscribe:@"/MQTTKit/example"
withCompletionHandler:nil];
}
}];

断开连接

[self.client disconnectWithCompletionHandler:^(NSUInteger code) {
// The client is disconnected when this completion handler is called
NSLog(@"MQTT client is disconnected");
}];

整个连接建立、发送消息、接受消息、断开连接都是通过Block的消息机制来实现，因此需要对block有很好地理解。