IOS network programming-synchronous and asynchronous connections of NSConnection

1 // 2 // ZFViewController. m 3 // 0628-Form Verification 4 // 5 // Created by zfan on 14-6-28. 6 // Copyright (c) 2014 zfan. all rights reserved. 7 // 8 9 # import "ZFViewController. h "10 # import" MBProgressHUD + MJ. h "11 12 @ interface ZFViewController () 13 14 @ property (weak, nonatomic) IBOutlet UITextField * userNameTextField; 15 @ property (weak, nonatomic) IBOutlet UITextField * passWordTextField; 16 17 @ end18 19 @ I Mplementation ZFViewController20 21-(void) viewDidLoad22 {23 [super viewDidLoad]; 24} 25 26-(IBAction) login :( id) sender27 {28 // verify that the account and password are valid 29 if (self. userNameTextField. text. length = 0) 30 {31 [MBProgressHUD showError: @ "enter an account"]; 32 return; 33} 34 35 if (self. passWordTextField. text. length = 0) 36 {37 [MBProgressHUD showError: @ "Enter Password"]; 38 return; 39} 40 41 // retrieve account and password 42 NSString * userName = self. userNam ETextField. text; 43 NSString * password = self. passWordTextField. text; 44 45 // generated URL46 NSString * urlPath = [NSString stringWithFormat: @ "http: // 192.168.1.101: 8080/ZFServer/login? Username = % @ & pwd = % @ ", userName, password]; 47 NSURL * url = [NSURL URLWithString: urlPath]; 48 49 // generate connection 50 NSURLRequest * urlRequest = [NSURLRequest requestWithURL: url]; 51 52 // establish a connection and receive the returned data (synchronously executed) 53 // NSData * loginData = [NSURLConnection sendSynchronousRequest: urlRequest returningResponse: nil error: nil]; 54 55 56 // establish a connection and receive returned data (asynchronously executed) 57 NSOperationQueue * queue = [[NSOperationQueue alloc] init]; 58 [NSURLConnection failed: urlRequest queue: queue completionHandler: ^ (NSURLResponse * response, NSData * data, NSError * connectionError) {59 NSData * loginData = data; 60 NSLog (@ "% ld", (unsigned long) loginData. length); 61}]; 62 63 // print the returned Data length 64 NSLog (@ "% @", self. userNameTextField. text); 65 NSLog (@ "% @", self. passWordTextField. text); 66 // NSLog (@ "% ld", (unsigned long) loginData. length); 67} 68 69 @ end

Knowledge points:

1> concatenate a string using the NSString method to generate a complete URL path;

2> Create an NSURLRequest connection instance using the URL using the NSURLRequest class method;

3> establish a connection through the NSConnection class method and accept the returned data. It can be implemented through synchronous and asynchronous methods:

 

3.1> synchronization mode

[NSURLConnection sendSynchronousRequest:urlRequest returningResponse:nil error:nil];

This method does not create a new thread, and the returned value is NSData. Because no new thread is created, the thread will not continue to run down before the method is completed, which may cause freezing;

 

3.2> asynchronous mode

NSOperationQueue *queue = [[NSOperationQueue alloc] init];[NSURLConnection sendAsynchronousRequest:urlRequest queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {　　NSData *loginData = data;　　NSLog(@"%ld", (unsigned long)loginData.length);}];

This method creates a new thread to accept the data returned by the network. The returned value is void. After the data is accepted, the statement in the block is executed;