简介：
在之前的项目中，很多是使用导航栏中视图层，通过KVC来获取网络状态，感觉这个方法有些投机取巧，到了iOS11，iPhoneX的导航栏视图层也进行了修改，除了蛋疼的UI，在获取使用以前获取网络状态的方法时候，果然炸了-_-
解决方案：
可以使用Reachability 的方案来解决该问题，GitHub地址，也可以去CSDN资源页下载。
OC代码：
#import <Foundation/Foundation.h>
#import <SystemConfiguration/SystemConfiguration.h>
//! Project version number for MacOSReachability.
FOUNDATION_EXPORT double ReachabilityVersionNumber;
//! Project version string for MacOSReachability.
FOUNDATION_EXPORT const unsigned char ReachabilityVersionString[];
/**
* Create NS_ENUM macro if it does not exist on the targeted version of iOS or OS X.
*
* @see http://nshipster.com/ns_enum-ns_options/
**/
#ifndef NS_ENUM
#define NS_ENUM(_type, _name) enum _name : _type _name; enum _name : _type
#endif
extern NSString *const kReachabilityChangedNotification;
typedef NS_ENUM(NSInteger, NetworkStatus) {
// Apple NetworkStatus Compatible Names.
NotReachable = 0,
ReachableViaWiFi = 2,
ReachableViaWWAN = 1
};
@class Reachability;
typedef void (^NetworkReachable)(Reachability * reachability);
typedef void (^NetworkUnreachable)(Reachability * reachability);
typedef void (^NetworkReachability)(Reachability * reachability, SCNetworkConnectionFlags flags);
@interface Reachability : NSObject
@property (nonatomic, copy) NetworkReachable reachableBlock;
@property (nonatomic, copy) NetworkUnreachable unreachableBlock;
@property (nonatomic, copy) NetworkReachability reachabilityBlock;
@property (nonatomic, assign) BOOL reachableOnWWAN;
+(instancetype)reachabilityWithHostname:(NSString*)hostname;
// This is identical to the function above, but is here to maintain
//compatibility with Apples original code. (see .m)
+(instancetype)reachabilityWithHostName:(NSString*)hostname;
+(instancetype)reachabilityForInternetConnection;
+(instancetype)reachabilityWithAddress:(void *)hostAddress;
+(instancetype)reachabilityForLocalWiFi;
-(instancetype)initWithReachabilityRef:(SCNetworkReachabilityRef)ref;
-(BOOL)startNotifier;
-(void)stopNotifier;
-(BOOL)isReachable;
-(BOOL)isReachableViaWWAN;
-(BOOL)isReachableViaWiFi;
// WWAN may be available, but not active until a connection has been established.
// WiFi may require a connection for VPN on Demand.
-(BOOL)isConnectionRequired; // Identical DDG variant.
-(BOOL)connectionRequired; // Apple's routine.
// Dynamic, on demand connection?
-(BOOL)isConnectionOnDemand;
// Is user intervention required?
-(BOOL)isInterventionRequired;
-(NetworkStatus)currentReachabilityStatus;
-(SCNetworkReachabilityFlags)reachabilityFlags;
-(NSString*)currentReachabilityString;
-(NSString*)currentReachabilityFlags;
@end代码概要：
1.Reachability中，包含了三个枚举类型，分别代表无网络，WiFi网络，数据网络
NotReachable = 0,
ReachableViaWiFi = 2,
ReachableViaWWAN = 1
2.也可以使用
-(BOOL)isReachable;
-(BOOL)isReachableViaWWAN;
-(BOOL)isReachableViaWiFi;
三个方法来获取当前是否支持某种网络类型
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使用方式：
1.将Reachability.h和Reachability.m拷贝到工程中，代码中导入Reachability.h
2.获取网络类型代码：
BOOL isExistenceNetwork = YES;
Reachability *reach = [Reachability reachabilityWithHostName:@"www.apple.com"];
switch ([reach currentReachabilityStatus]) {
case NotReachable:
isExistenceNetwork = NO;
NSLog(@"Current Reachability Status : notReachable");
break;
case ReachableViaWiFi:
isExistenceNetwork = YES;
NSLog(@"Current Reachability Status : WIFI");
break;
case ReachableViaWWAN:
isExistenceNetwork = YES;
NSLog(@"Current Reachability Status : 3/4G");
break;
default:
break;
}