IOS uses nsurlsession to download large files

Nsurlsession *session = [Nsurlsession sharedsession];

Can not be like connection with agent monitoring, directly download files, but is unable to obtain the progress of the download

nsurlsessiondownloadtask *task = [session

Downloadtaskwithurl:[nsurl urlwithstring:@ ""]

completionhandler:^ (Nsurl * _nullable location, Nsurlresponse * _nullable response, Nserror * _nullable error) {

//real path to file storage

NSString *file = [[Nssearchpathfordirectoriesindomains (nscachesdirectory, Nsuserdomainmask, YES) lastObject ] StringByAppendingPathComponent:response.suggestedFilename];

//Cut temporary files for location to the real path

Nsfilemanager *mgr = [Nsfilemanager Defaultmanager];

[Mgr moveitematurl: Location tourl:[Nsurl Fileurlwithpath:file] error:nil];

}];

[Task resume];

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Three protocols, but the most basic of which is the inheritance of the Protocol

@interface Viewcontroller () <nsurlsessionDatadelegate>//inheriting subclasses is equivalent to inheriting the parent class protocol

@end

Inheritance relationship between protocols: <nsurlsessionDatadelegate>:<nsurlsessionTaskdelegate>:< Nsurlsessiondelegate>

@implementation Viewcontroller

-(void) Viewdidload {

[Super Viewdidload];

Nsurlsession *session = [Nsurlsession sharedsession];

Session.delegate = self; Cannot directly set delegate is ReadOnly

Can only be created at the beginning of its agent

Nsurlsession *session = [nsurlsession sessionwithconfiguration: [nsurlsessionconfiguration Defaultsessionconfiguration] Delegate: self delegatequeue:[[nsoperationqueue alloc] init]];

Parent protocol, but can pass in sub-protocol: Nullable ID <NSURLSessionDelegate>

Nsurlsessiondownloadtask *task = [Session downloadtaskwithrequest:[nsurlrequest Requestwithurl:[nsurl URLWithString: @ ""]] completionhandler:^ (nsurl * _nullable location, Nsurlresponse * _nullable response, Nserror * _nullable error) {}];

[Task resume];

}

Proxy method

-(void) Urlsession: (Nsurlsession *) session Datatask: (Nsurlsessiondatatask *) datatask didreceiveresponse:( Nsurlresponse *) Response Completionhandler: (void (^) (nsurlsessionresponsedisposition)) completionhandler{

To start, otherwise it cannot be downloaded

Completionhandler (Nsurlsessionresponseallow);//Allow to continue request number after

}

-(void) Urlsession: (Nsurlsession *) session Datatask: (Nsurlsessiondatatask *) datatask didreceivedata:( NSData *) data{

}

-(void) Urlsession: (Nsurlsession *) session Task: (Nsurlsessiontask *) Task Didcompletewitherror: (Nserror *) error{

}

IOS uses nsurlsession to download large files