我怎么写< 1100>或< 2200>到我的CBPeripheral上的特征值？ [英] How do I write <1100> or <2200> to the value of a characteristic on my CBPeripheral?

问题描述

当我 NSLog特征。值时，它显示为< 1100> 或 < 2200> 。我知道这是一个十六进制。当我更改值时，我很困惑要写什么。

When I NSLog characteristic.value it shows as either <1100> or <2200>. I know this is a hexadecimal. I'm confused as what to write when I'm changing the value.

任何帮助将不胜感激。

目前，我正在执行以下操作，但更改值时为null。

At the moment I'm doing the following, but getting null when I change the values.

- (IBAction)deviceSwitchPressed:(id)sender {
    if ([sender isOn]) {
        [activePeripheral writeValue:[@"1100" dataUsingEncoding:NSUTF8StringEncoding] forCharacteristic:switchCharacterictic type:CBCharacteristicWriteWithResponse];
    } else {
        [activePeripheral writeValue:[@"2200" dataUsingEncoding:NSUTF8StringEncoding] forCharacteristic:switchCharacterictic type:CBCharacteristicWriteWithResponse];
    }

    NSLog(@"characteristic.value = %@", switchCharacterictic.value);

}

推荐答案

我用来将十六进制字符串值转换为数据对象的内容。

This is what I use to convert hex string values into data objects.

NSString *command = hexString;
command = [command stringByReplacingOccurrencesOfString:@" " withString:@""];
NSMutableData *commandToSend= [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < [command length]/2; i++) {
    byte_chars[0] = [command characterAtIndex:i*2];
    byte_chars[1] = [command characterAtIndex:i*2+1];
    whole_byte = strtol(byte_chars, NULL, 16);
    [commandToSend appendBytes:&whole_byte length:1];
}

但是向特征中写入值并不能保证回。外设可以根据需要随时处理该数据。

However writing a value to a characteristic doesn't guarantee that is what will be returned. The peripheral can handle that data in anyway that it wants.

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