我可以在iOS7的其他ViewController中使用NSURLSession委托方法吗？

Question

I am using iOS7 and Xcode 5.

I have instantiated a NSURLSession object with a URL in one ViewController and then I want to write its delegate in a different ViewController. Is it possible?

Basically, I want to make the call in one ViewController, and immediately after making the call I transit to the other ViewController. Once the transition is made, I want to receive the response in the second ViewController through the NSURLSession delegate methods and then display the data. Is this possible?

Note: I don't want to keep the user waiting in the first ViewController until the server comes back with its response, because while the server is processing the data, I can keep the user engaged in the second ViewController with other images/elements displayed.

Answer 1

Your Api.h

#import <Foundation/Foundation.h>
typedef void(^successTypeBlock)(NSData*);
typedef void(^errorTypeBlock)(NSError*);
@interface TestApi : NSObject<NSURLConnectionDelegate>

-(void)hitApiWithURL:(NSURL*)url successBlock:(successTypeBlock)success  failureBlock:(errorTypeBlock)failure;
@end

your Api.m

@interface  TestApi()
{

}
@property(nonatomic,copy) errorTypeBlock    errorBlock_;
@property(nonatomic,copy) successTypeBlock  successBlock_;
@end
@implementation TestApi


-(void)hitApiWithURL:(NSURL*)url successBlock:(successTypeBlock)success  failureBlock:(errorTypeBlock)failure{
    errorBlock_=failure;
    successBlock_=success;
    NSURLRequest   *request=[NSURLRequest requestWithURL:url];
    [NSURLConnection connectionWithRequest:request delegate:self];

}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{

}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data

{
    successBlock_(data);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{



}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    errorBlock_(error);
}



@end

Now

[<yourApiObj>   hitApiWithURL:<your URL> successBlock:^(NSData* data){
//get success value here after server responce

}  failureBlock:^(NSError* error){

//get error if any
}];

just gave you a basic skeleton improve and innovate as per your needs.

Answer 2

Rather than doing it on the main thread I think you need use threading concept so that, you can accomplish this using the secondary thread. And even the UI will not get blocked.

Write a class and subclass it with NSOperation.

refer this

1. Apple's Sample code : https://developer.apple.com/library/mac/samplecode/NSOperationSample/Introduction/Intro.html#//apple_ref/doc/uid/DTS10004184

2. Refer this wonderfull tutorial. http://www.raywenderlich.com/19788/how-to-use-nsoperations-and-nsoperationqueues

Hope this will help you.