监控蓝牙的状态：
1.引入#import <CoreBluetooth/CoreBluetooth.h>蓝牙框架
2.遵循其代理 CBPeripheralManagerDelegate
3.创建蓝牙对象 CBPeripheralManager *manager = [[CBPeripheralManager alloc] initWithDelegate:self queue:nil];
4.实现其代理事件
-(void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral{
switch (peripheral.state) {
case CBCentralManagerStateUnknown:
NSLog(@"未知状态");
break;
case CBCentralManagerStateResetting:
NSLog(@"正在重置");
break;
case CBCentralManagerStateUnsupported:
NSLog(@"不支持蓝牙设备");
break;
case CBCentralManagerStateUnauthorized:
NSLog(@"未授权");
break;
case CBPeripheralManagerStatePoweredOn:
NSLog(@"蓝牙打开");
break;
case CBPeripheralManagerStatePoweredOff:
NSLog(@"蓝牙关闭");
break;
default:
break;
}
}