IOS development-iOS network programming asynchronous GET Method Request Programming

Connection: didReceiveData: the request is successful and starts to receive data. If the data volume is large, it will be called multiple times;

Connection: didFailWithError: An exception occurred when loading data;

ConnectionDidFinishLoading: The data is successfully loaded and executed after the connection: didReceiveData method;

The MasterViewController. h code for the master View Controller Using asynchronous requests is as follows:

[Cpp]? # Import <UIKit/UIKit. h>
 
# Import "NSString + URLEncoding. h"
 
# Import "NSNumber + Message. h"
 

 
@ Interface MasterViewController: UITableViewController <NSURLConnectionDelegate>
 

 
@ Property (strong, nonatomic) DetailViewController * detailViewController;
 
// Save the data list
 
@ Property (nonatomic, strong) NSMutableArray * listData;
 

 
// Receives the data returned from the slave server.
 
@ Property (strong, nonatomic) NSMutableData * datas;
 

 
// Reload the table View
 
-(Void) reloadView :( NSDictionary *) res;
 

 
// Start requesting Web Service
 
-(Void) startRequest;
 

 
@ End

# Import <UIKit/UIKit. h>

# Import "NSString + URLEncoding. h"

# Import "NSNumber + Message. h"

 

@ Interface MasterViewController: UITableViewController <NSURLConnectionDelegate>

 

@ Property (strong, nonatomic) DetailViewController * detailViewController;

// Save the data list

@ Property (nonatomic, strong) NSMutableArray * listData;

 

// Receives the data returned from the slave server.

@ Property (strong, nonatomic) NSMutableData * datas;

 

// Reload the table View

-(Void) reloadView :( NSDictionary *) res;

 

// Start requesting Web Service

-(Void) startRequest;

 

@ End

The above code implements the NSURLConnectionDelegate protocol in the MasterViewController definition. The datas attribute is used to store the data returned from the server and is defined as a variable type. It is used to continuously append data to this datas during the loading of data from the server. The MasterViewController. m code is as follows:

[Cpp]/*
 
* Start to request Web Service
 
*/
 
-(Void) startRequest {
 
NSString * strURL = [[NSString alloc] initWithFormat:
 
@ "Http: // iosbook3/mynotes/webservice. php? Email =%@ & type =%@ & action =% @",
 
@ "<Your iosbook1.com user email>", @ "JSON", @ "query"];
 
NSURL * url = [NSURL URLWithString: [strURL URLEncodedString];
 
NSURLRequest * request = [[NSURLRequest alloc] initWithURL: url];
 
NSURLConnection * connection = [NSURLConnection alloc]
 
InitWithRequest: request
 
Delegate: self];
 
If (connection ){
 
_ Datas = [NSMutableData new];
 
}
 
}
 

 
# Pragma mark-NSURLConnection callback Method
 
-(Void) connection :( NSURLConnection *) connection didReceiveData :( NSData *) data {①
 
[_ Datas appendData: data];
 
}
 

 
-(Void) connection :( NSURLConnection *) connection didFailWithError: (NSError *) error {
 
NSLog (@ "% @", [error localizedDescription]);
 
}
 
-(Void) connectionDidFinishLoading: (NSURLConnection *) connection {②
 
NSLog (@ "request completed ...");
 
NSDictionary * dict = [NSJSONSerialization JSONObjectWithData: _ datas
 
Options: NSJSONReadingAllowFragments error: nil];
 
[Self reloadView: dict];
 
}

/*

* Start to request Web Service

*/

-(Void) startRequest {

NSString * strURL = [[NSString alloc] initWithFormat:

@ "Http: // iosbook3/mynotes/webservice. php? Email =%@ & type =%@ & action =% @",

@ "<Your iosbook1.com user email>", @ "JSON", @ "query"];

NSURL * url = [NSURL URLWithString: [strURL URLEncodedString];

NSURLRequest * request = [[NSURLRequest alloc] initWithURL: url];

NSURLConnection * connection = [NSURLConnection alloc]

InitWithRequest: request

Delegate: self];

If (connection ){

_ Datas = [NSMutableData new];

}

}

 

# Pragma mark-NSURLConnection callback Method

-(Void) connection :( NSURLConnection *) connection didReceiveData :( NSData *) data {①

[_ Datas appendData: data];

}

 

-(Void) connection :( NSURLConnection *) connection didFailWithError: (NSError *) error {

NSLog (@ "% @", [error localizedDescription]);

}

-(Void) connectionDidFinishLoading: (NSURLConnection *) connection {②

NSLog (@ "request completed ...");

NSDictionary * dict = [NSJSONSerialization JSONObjectWithData: _ datas

Options: NSJSONReadingAllowFragments error: nil];

[Self reloadView: dict];

}

In the connection: didReceiveData: Method of row ①, it is very important to understand this point by continuously receiving data from the server through the [_ datas appendData: data] statement. If the load is successful, the connectionDidFinishLoading of row ② will be called back. This method also means the end of the request. At this time, the data in _ datas is complete, send the data back to the View Controller of the presentation layer.