如何在iPhone中检查NetConnection是否可用？

https://stackoverflow.com/questions/6371887

28-10-2019
|

题

我有一个应用程序，我的登录表单用户名和密码 textfields. 。当用户输入其用户名和密码并单击“提交”按钮时，它将转到服务器API数据库，并检查用户是否有效。如果不是连接，则在SQLite数据库中检查其值。

如果在SQLITE数据库中，如果用户用户名和密码已验证，则允许用户输入该应用程序，否则他必须注册。我尝试了以下代码，但是现在我很困惑应该放置我的代码。

我有检查服务器连接和SQLITE连接。我的答案是，如果用户一次又一次地登录，则用户名和密码应始终从SQLITE数据库中的服务器首先检查。如果服务器关闭，则用户名和密码应从SQLITE数据库检查。

这是我的代码：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkNetworkStatus:) name:kReachabilityChangedNotification object:nil];

    internetReachable = [[Reachability reachabilityForInternetConnection] retain];
    [internetReachable startNotifier];

    // check if a pathway to a random host exists
    hostReachable = [[Reachability reachabilityWithHostName: @"www.apple.com"] retain];
    [hostReachable startNotifier];

回调如下；

- (void) checkNetworkStatus:(NSNotification *)notice
{
    // called after network status changes

    NetworkStatus internetStatus = [internetReachable currentReachabilityStatus];
    switch (internetStatus)

    {
        case NotReachable:
        {
            break;

        }
        case ReachableViaWiFi:
        {
            break;

        }
        case ReachableViaWWAN:
        {
            break;

        }
    }

    NetworkStatus hostStatus = [hostReachable currentReachabilityStatus];
    switch (hostStatus)

    {
        case NotReachable:
        {
            break;

        }
        case ReachableViaWiFi:
        {
            break;

        }
        case ReachableViaWWAN:
        {
            break;

        }
    }
}

这是我的API控制器，我从API服务器中获取值并在SQLITE数据库中插入值：

//
//  apicontroller.m
//  apitest
//
//  Created by raji.nair on 6/10/11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "apicontroller.h"
#import "Result.h"
#import "global.h"

#import <sqlite3.h>
#define DATABASE_NAME @"journey.sqlite"
#define DATABASE_TITLE @"journey"



@implementation apicontroller
@synthesize  txtUserName;
@synthesize txtPassword;
@synthesize txtfirstName;
@synthesize txtlast;
@synthesize txtEmail;
@synthesize webData;    

- (NSString *) getWritableDBPath {

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES);
    NSString *documentsDir = [paths objectAtIndex:0];
    return [documentsDir stringByAppendingPathComponent:DATABASE_NAME];
}

-(void)createEditableCopyOfDatabaseIfNeeded 
{
    // Testing for existence
    BOOL success;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                         NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:DATABASE_NAME];
    NSLog(@"%@",writableDBPath);

    success = [fileManager fileExistsAtPath:writableDBPath];
    if (success)
        return;

    // The writable database does not exist, so copy the default to
    // the appropriate location.
    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath]
                               stringByAppendingPathComponent:DATABASE_NAME];
    success = [fileManager copyItemAtPath:defaultDBPath
                                   toPath:writableDBPath
                                    error:&error];
    if(!success)
    {
        NSAssert1(0,@"Failed to create writable database file with Message : '%@'.",
                  [error localizedDescription]);
    }
}

-(void)sendRequest
{
    UIDevice *device = [UIDevice currentDevice];
    NSString *udid = [device uniqueIdentifier];
    NSString *sysname = [device systemName];
    NSString *sysver = [device systemVersion];
    NSString *model = [device model];
    NSLog(@"idis:%@",[device uniqueIdentifier]);
    NSLog(@"system nameis :%@",[device systemName]);
    NSLog(@"System version is:%@",[device systemVersion]);
    NSLog(@"System model is:%@",[device model]);
    NSLog(@"device orientation is:%d",[device orientation]);
    NSString *post = [NSString stringWithFormat:@"Loginkey=%@&Password=%@&DeviceCode=%@&Firmware=%@&IMEI=%@",txtUserName.text,txtPassword.text,model,sysver,udid];
    NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES]; 
    NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]]; 
    NSLog(@"%@",postLength);
    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease]; 
    [request setURL:[NSURL URLWithString:@"http://192.168.0.68:91/JourneyMapperAPI?RequestType=Login"]]; 
    [request setHTTPMethod:@"POST"]; 
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; 
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"]; 
    [request setHTTPBody:postData];

    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

    if (theConnection) {
        webData = [[NSMutableData data] retain];
        NSLog(@"%@",webData);
    }
    else 
    {

    }

}

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
{   
    [webData setLength: 0]; 
} 

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{         
    [webData appendData:data]; 

} 

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{     
    [connection release];  
    [webData release]; 

} 

-(void)connectionDidFinishLoading:(NSURLConnection *)connection 
{      
    NSString *loginStatus = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding]; 
    NSLog(@"%@",loginStatus);  

    NSString *json_string = [[NSString alloc] initWithData:webData encoding:NSUTF8StringEncoding]; 

    NSDictionary *result = [json_string JSONValue];
    NSArray *values = [result objectForKey:@"Result"];
    NSMutableArray *results = [[NSMutableArray alloc] init];

    for (int index = 0; index<[values count]; index++) {
        NSMutableDictionary * value = [values objectAtIndex:index];
        Result * result = [[Result alloc] init];
        result.UserID = [value objectForKey:@"UserId"];
        result.FirstName = [value objectForKey:@"FirstName"];
        result.LastName =[value objectForKey:@"LastName"];
        result.Email =[value objectForKey:@"Email"];
        result.ProfileImage =[value objectForKey:@"ProfileImage"];
        result.ThumbnailImage =[value objectForKey:@"ThumbnailImage"];
        result.DeviceInfoId =[value objectForKey:@"DeviceInfoId"];
        NSLog(@"%@",result.UserID);


        [results addObject:result];
        [result release]; 
    }



    for (int index = 0; index<[results count]; index++) {
        Result * result = [results objectAtIndex:index];
        //save the object variables to database here


        [self createEditableCopyOfDatabaseIfNeeded];

        NSString *filePath = [self getWritableDBPath];

        sqlite3 *database;

        if(sqlite3_open([filePath UTF8String], &database) == SQLITE_OK) {
            NSDate *dt = [NSDate date]; //get current date
            NSString *timestamp = [dt description];
            NSString *journeyid = [NSString stringWithFormat:@"%@_%@_%@", result.UserID, result.DeviceInfoId, timestamp];

            const char *sqlStatement = "insert into UserInformation(UserID,DeviceId,FirstName,Email,JourneyID) VALUES (?,?,?,?,?)";
            sqlite3_stmt *compiledStatement;
            if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK)    {
                sqlite3_bind_text( compiledStatement, 1, [result.UserID UTF8String],-1,SQLITE_TRANSIENT);
                sqlite3_bind_text(compiledStatement, 2, [result.DeviceInfoId UTF8String],-1,SQLITE_TRANSIENT);
                sqlite3_bind_text (compiledStatement, 3, [result.FirstName UTF8String],-1,SQLITE_TRANSIENT);
                sqlite3_bind_text (compiledStatement, 4, [result.Email UTF8String],-1,SQLITE_TRANSIENT);
                sqlite3_bind_text(compiledStatement, 5, [journeyid UTF8String], -1, SQLITE_TRANSIENT);

            }
            if(sqlite3_step(compiledStatement) != SQLITE_DONE ) {
                NSLog( @"Save Error: %s", sqlite3_errmsg(database) );
            }
            else {
                UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"UIAlertView" message:@"Record added" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
                [alert show];
                [alert release];
                alert = nil;
            }

            sqlite3_finalize(compiledStatement);
        }
        sqlite3_close(database);
    }

    [loginStatus release];           
    [connection release];  
    [webData release]; 
} 

-(IBAction)click:(id)sender
{
    [self sendRequest];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    [txtfirstName resignFirstResponder];
    [txtlast resignFirstResponder];
    [txtUserName resignFirstResponder];
    [txtPassword resignFirstResponder];
    [txtEmail resignFirstResponder];
}
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {


    [super viewDidLoad];
    //[self sendRequest];
}

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc. that aren't in use.
}

- (void)viewDidUnload {
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}


- (void)dealloc {
    [super dealloc];
}


@end

这是我创建JSON对象的NSString变量的类：

//
//  Result.h
//  apitest
//
//  Created by pradeep.yadav on 6/14/11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import <Foundation/Foundation.h>


//TokenID":"Vao13gifem","isError":false,"ErrorMessage":"","Result":[{"UserId":"153","FirstName":"Rocky","LastName":"Yadav","Email":"rocky@itg.com","ProfileImage":null,"ThumbnailImage":null,"DeviceInfoId":"12"}],"ErrorCode":900}
//Terminating in response to SpringBoard's termination.



@interface Result : NSObject {

    NSString * UserID;
    NSString *FirstName;
    NSString *LastName;
    NSString *Email;
    NSString *ProfileImage;
    NSString *ThumbnailImage;
    NSString *DeviceInfoId;
}
@property (nonatomic,retain) NSString *UserID;
@property (nonatomic,retain) NSString *FirstName;
@property (nonatomic,retain) NSString *LastName;
@property (nonatomic,retain) NSString *Email;
@property (nonatomic,retain) NSString *ProfileImage;
@property (nonatomic,retain) NSString *ThumbnailImage;
@property (nonatomic,retain) NSString *DeviceInfoId;

@end



//
//  Result.m
//  apitest
//
//  Created by pradeep.yadav on 6/14/11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "Result.h"


@implementation Result
@synthesize UserID;
@synthesize FirstName;
@synthesize LastName;
@synthesize Email;
@synthesize ProfileImage;
@synthesize ThumbnailImage;
@synthesize DeviceInfoId;





- (void)dealloc {
    [super dealloc];
    [UserID release];
    [FirstName release];
    [LastName release];
    [Email release];
    [ProfileImage release];
    [ThumbnailImage release];
    [DeviceInfoId release];
}


@end

如果无法通过NetConnection获得我的服务器API，则应从数据库中获取和验证我的用户名和密码值。

解决方案

 NSMutableURLRequest * serviceRequest = [NSMutableURLRequest requestWithURL:serviceUrl];
[serviceRequest setValue:@"text/xml" forHTTPHeaderField:@"Content-type"];
[serviceRequest setHTTPMethod:@"POST"];
[serviceRequest setHTTPBody:[xmlString dataUsingEncoding:NSUTF8StringEncoding]];
NSData *responseData;
NSURLResponse * serviceResponse;
NSError * serviceError;
responseData = [NSURLConnection sendSynchronousRequest:serviceRequest returningResponse:&serviceResponse error:&serviceError];
NSString *resp=[[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
NSLog(@"RETRIEVING:%@",resp);

if(responseData != NULL)
{
//connection exist
}
else
{
//Connection doesn't exist
}

其他提示

节目晚了，但是检查此问题的最佳解决方案是可及性。可达性是由Apple写为“示例代码”的，但这是迄今为止优雅地处理网络状态的最完整方法。查看可及性指南.

这是有关如何使用可及性的一些信息： iOS 4的可及性指南

我已经回顾了您的问题。我认为您应该遵循以下流程：

用户将以登录表单输入“用户名”和“密码”。
然后首先检查本地数据库。
如果用户存在，则用户可以引导登录并访问该应用程序。
如果用户不存在，请从实时服务器中检查其凭据。
如果用户有效，请将用户名和密码输入本地数据库。这样，下次他可以直接登录。
如果用户无效，请简单地提供拒绝访问的消息。

现在，要检查网络连接：为此，请进行一个Web视图（Web-View将是看不见的）。然后打开简单的网站，例如http://www.google.com”以及实现Web-View委托方法。

在Web-View委托法中：

- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error{

    [self connectionFailed:error];
}

以下是“连接”函数：

-(void)connectionFailed:(NSError *)error{

if ([error code] == -999) {
    //show error alert, etc.
    //NSLog(@"-999 Detected, Do Nothing");
    //NSLog([error localizedDescription]);
}   
else if([error code] == -1009 || [[error localizedDescription] isEqualToString:@"no Internet connection"]){
    [self hideLoading];
    [connectionView loadHTMLString:@"<body bgcolor=#58637C><br><br><br><br><font size=5 color=white>Please turn on your Internet connection to access this application.</font></body>" baseURL:nil];
    [connectionView setFrame:CGRectMake(0.0, 0.0, 320.0, 431.0)];
    [self.view addSubview:connectionView];
}
else if([error code] == -1001 || [[error localizedDescription] isEqualToString:@"timed out"]){
    [self hideLoading];
    [connectionView loadHTMLString:@"<body bgcolor=#58637C><br><br><br><br><font size=5 color=white>Request Timed Out.</font></body>" baseURL:nil];
    [connectionView setFrame:CGRectMake(0.0, 0.0, 320.0, 431.0)];
    [self.view addSubview:connectionView];
}
else if (error != NULL) {
    [self hideLoading];
    [connectionView loadHTMLString:@"<body bgcolor=#58637C><br><br><br><br><font size=5 color=white>Error loading page, Please try again later.</font></body>" baseURL:nil];
    [connectionView setFrame:CGRectMake(0.0, 0.0, 320.0, 431.0)];
    [self.view addSubview:connectionView];
}
else{       
}
}

在这里，ConnectionView视图是另一个Web视图。您可以将代码用适当的消息替换为uialerview。

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