檢測網絡狀態

在網絡應用中，需要對用戶設備的網絡狀態進行實時監控，目的是
讓用戶了解自己的網絡狀態，防止一些誤會（比如怪應用無能）
根據用戶的網絡狀態進行智能處理，節省用戶流量，提高用戶體驗
WIFI\3G網絡：自動下載高清圖片
低速網絡：只下載縮略圖
沒有網絡：只顯示離線的緩存數據

蘋果官方提供了一個叫Reachability的示例程序，便於開發者檢測網絡狀態
https://developer.apple.com/library/ios/samplecode/Reachability/Reachability.zip

Reachability的使用步驟
添加框架SystemConfiguration.framework

添加源代碼

包含頭文件

#import "Reachability.h"

抽取工具類

常見用法
// 是否WIFI
+ (BOOL) IsEnableWIFI {
    return ([[Reachability reachabilityForLocalWiFi] currentReachabilityStatus] != NotReachable);
}

// 是否3G
+ (BOOL) IsEnable3G {
    return ([[Reachability reachabilityForInternetConnectionen] currentReachabilityStatus] != NotReachable);
}

網絡監控

[[NSNotificationCenter defaultCenter] addObserver:self
 selector:@selector(reachabilityChanged:) name: kReachabilityChangedNotification object: nil];
self.netReachability = [Reachability reachabilityForInternetConnection];
[self.netReachability startNotifier];

- (void)dealloc
{
    [self.netReachability stopNotifier];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:kReachabilityChangedNotification object:nil];
}

檢測網絡狀態實例

NetWorkTool工具類

#import 

@interface NetworkTool : NSObject
/**
 *  是否WIFI
 */
+ (BOOL)isEnableWIFI;

/**
 *  是否3G
 */
+ (BOOL)isEnable3G;
@end

#import "NetWorkTool.h"
#import "Reachability.h"

@implementation NetworkTool
// 是否WIFI
+ (BOOL)isEnableWIFI {
    return ([[Reachability reachabilityForLocalWiFi] currentReachabilityStatus] != NotReachable);
}

// 是否3G
+ (BOOL)isEnable3G {
    return ([[Reachability reachabilityForInternetConnection] currentReachabilityStatus] != NotReachable);
}
@end

實現類

#import "ViewController.h"
#import "Reachability.h"
#import "NetworkTool.h"

@interface ViewController ()
@property (nonatomic, strong) Reachability *reachability;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 監聽網絡狀態發生改變的通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(networkStateChange) name:kReachabilityChangedNotification object:nil];

    // 獲得Reachability對象
    self.reachability = [Reachability reachabilityForInternetConnection];
    // 開始監控網絡
    [self.reachability startNotifier];

}

- (void)dealloc
{
    [self.reachability stopNotifier];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)networkStateChange
{
    NSLog(@"網絡狀態改變了");
    [self checkNetworkState];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self checkNetworkState];
}

#pragma mark - App應用程序網絡類型改變就會調用
- (void)networkStateChange
{
    if ([NetWorkTool isEnableWIFI]) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"溫馨提示您" message:@"您現在網絡環境為wifi！開始暢享吧！" delegate:self cancelButtonTitle:@"確定" otherButtonTitles:nil, nil];
        [alert show];
    } else if ([NetWorkTool isEnable3G]) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"溫馨提示您"  message:@"您現在網絡環境為3G/4G網絡！" delegate:self cancelButtonTitle:@"確定" otherButtonTitles:nil, nil];
        [alert show];
    } else {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"溫馨提示您" message:@"您當前沒有可連的網絡或已經掉線！" delegate:self cancelButtonTitle:@"確定" otherButtonTitles:nil, nil];
        [alert show];
    }
}