来自NSURLConnection的iOs NSURLConnection为零

Question

我想知道是否有人能指出为什么我不能捕捉到一个网络回复。我的NSLog显示，在连接的整个运行过程中，[NSMutableData receivedData]的长度为0。单击登录按钮时单击的脚本将返回一个字符串。我的NSLog结果粘贴在下面，之后我粘贴了我所拥有的.h和.m文件。

NSLog结果

2012-11-28 23:35:22.083 [12548:c07] Clicked on button_login
2012-11-28 23:35:22.090 [12548:c07] theConnection is succesful
2012-11-28 23:35:22.289 [12548:c07] didReceiveResponse
2012-11-28 23:35:22.290 [12548:c07] didReceiveData
2012-11-28 23:35:22.290 [12548:c07] 0
2012-11-28 23:35:22.290 [12548:c07] connectionDidFinishLoading
2012-11-28 23:35:22.290 [12548:c07] 0

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

// Create an Action for the button.
- (IBAction)button_login:(id)sender;

// Add property declaration.
@property (nonatomic,assign) NSMutableData *receivedData;

@end

ViewController.m

#import ViewController.h

@interface ViewController ()
@end

@implementation ViewController

@synthesize receivedData;

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"didReceiveResponse");    
    [receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {    
    NSLog(@"didReceiveData");    
    [receivedData appendData:data];
    NSLog(@"%d",[receivedData length]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {    
    NSLog(@"connectionDidFinishLoading");
    NSLog(@"%d",[receivedData length]);
}

- (IBAction)button_login:(id)sender {

    NSLog(@"Clicked on button_login");    
    NSString *loginScriptURL = [NSString stringWithFormat:@"http://www.website.com/app/scripts/login.php?"];

    NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:loginScriptURL]];

    NSString *postString = [NSString stringWithFormat:@"&paramUsername=user&paramPassword=pass"];
    NSData *postData = [postString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

    [theRequest setHTTPMethod:@"POST"];
    [theRequest setHTTPBody:postData];

    // Create the actual connection using the request.
    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

    // Capture the response
    if (theConnection) {        
        NSLog(@"theConnection is succesful");        
    } else {        
        NSLog(@"theConnection failed");
    }
}
@end

Answer 1

问题是您没有初始化receivedData实例。只要改变你的财产，就像：

@property (nonatomic, retain) NSMutableData *receivedData;

并更改方法，如：

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"didReceiveResponse");    
    [self.receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{    
    NSLog(@"didReceiveData");    
    [self.receivedData appendData:data];
    NSLog(@"%d",[receivedData length]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{    
    NSLog(@"connectionDidFinishLoading");
    NSLog(@"%d",[receivedData length]);
}

- (IBAction)button_login:(id)sender
{

    NSLog(@"Clicked on button_login");    
    NSString *loginScriptURL = [NSString stringWithFormat:@"http://www.website.com/app/scripts/login.php?"];

    NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:loginScriptURL]];

    NSString *postString = [NSString stringWithFormat:@"&paramUsername=user&paramPassword=pass"];
    NSData *postData = [postString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

    [theRequest setHTTPMethod:@"POST"];
    [theRequest setHTTPBody:postData];

    // Create the actual connection using the request.
    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

    // Capture the response
    if (theConnection)
    {        
        NSLog(@"theConnection is succesful");  
        self.receivedData = [NSMutableData data];      
    } else
    {        
        NSLog(@"theConnection failed");
    }
}

Answer 2

您可以尝试下面的代码可能对您有所帮助。

- (IBAction)button_login:(id)sender {

    NSLog(@"Clicked on button_login");  
            NSMutableDictionary *dictionnary = [NSMutableDictionary dictionary];
            [dictionnary setObject:@"user"  forKey:@"Username"];
            [dictionnary setObject:@"pass" forKey:@"Password"];

            NSError *error = nil;
            NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionnary
                                                               options:kNilOptions
                                                                 error:&error];   

            NSString *urlString = @"Sample URL";

            NSURL *url = [NSURL URLWithString:urlString];
     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
            [request setHTTPMethod:@"POST"];

            [request setHTTPBody:jsonData];
            NSURLResponse *response = NULL;
            NSError *requestError = NULL;
            NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&requestError];
            NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding] ;
             NSLog(@"%@", responseString); 

}

如果是GET请求，那么可以尝试链接：/login.php?username=admin&password=1212‌​3吗？

- (IBAction)button_login:(id)sender {

    NSLog(@"Clicked on button_login");  
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"/login.php?username=adm‌​in&password=1212‌​3"]];

     // Perform request and get JSON as a NSData object


    NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
     NSLog(@"response=%@",response ); 

}

并使用这段代码。