iOS Development Network Chapter-File download (three • progress bar)

First, to achieve the download file progress control

1. Code examples

1 #import "YYViewController.h"2 3 @interfaceYyviewcontroller ()4@property (nonatomic,strong) Nsmutabledata *FileData;5@property (nonatomic,strong) Nsfilehandle *Writehandle;6@property (nonatomic,assign)Long Longcurrentlength;7@property (nonatomic,assign)Long Longsumlength;8@property (Weak, nonatomic) Iboutlet Uiprogressview *progress;9 Ten-(ibaction) star; One  A @end -  - @implementationYyviewcontroller the  -- (void) Viewdidload - { - [Super Viewdidload]; + } -  +-(ibaction) star { A      at      -     //Create a download path -      -Nsurl *url=[nsurl urlwithstring:@"Http://192.168.0.109:8080/MJServer/resources/video.zip"]; -      -     //Create a request inNsurlrequest *request=[Nsurlrequest Requestwithurl:url]; -      to     //send a request (using proxy method) + //nsurlconnection *connt= -[Nsurlconnection Connectionwithrequest:requestDelegate: self]; the //[connt start]; *    $ }Panax Notoginseng  - #pragmaMark-nsurlconnectiondatadelegate Proxy method the /* + * When the response to the server is received (the server is connected) , the A  */ the-(void) Connection: (Nsurlconnection *) connection didreceiveresponse: (Nsurlresponse *) Response + { -     //1. Create a file storage path $NSString *caches=[Nssearchpathfordirectoriesindomains (Nscachesdirectory, Nsuserdomainmask, YES) lastobject]; $NSString *filepath=[caches stringbyappendingpathcomponent:@"Video.zip"]; -  -      the      -     //2. Create an empty file into the sandboxWuyiNsfilemanager *mgr=[Nsfilemanager Defaultmanager]; the     //the size you just created is o bytes - [Mgr Createfileatpath:filepath contents:nil Attributes:nil]; Wu      -     //3. Create a file handle to write data Aboutself.writehandle=[Nsfilehandle Filehandleforwritingatpath:filepath]; $      -     //4. Get the full length of the file -Self.sumlength=response.expectedcontentlength; - } A  + /* the * Called when data is received from the server (may be called multiple times, only partial data is passed at a time) -  */ $-(void) Connection: (Nsurlconnection *) connection didreceivedata: (NSData *) Data the { the     //accumulate the received data theself.currentlength+=data.length; the      -     //calculates the current progress (converted to double type) in     DoubleProgress= (Double) self.currentlength/self.sumlength; theself.progress.progress=progress; the      About     //1.1 points to receive data.  theNSLog (@"receive data from the server! ---%d", data.length); the      the     //writes data to the created empty file, but cannot use WriteToFile (overwrites) +     //move to the end of a file - [Self.writehandle seektoendoffile]; the     //writes data from the position currently being movedBayi [Self.writehandle Writedata:data]; the } the  - /* - * When the server's data is loaded, it will be called the  */ the-(void) Connectiondidfinishloading: (Nsurlconnection *) Connection the { theNSLog (@"Download Complete"); -      the     //closes the connection and no longer enters data in the file the [Self.writehandle CloseFile]; the     //destroyed94self.writehandle=Nil; the      the     //after the download is complete, clear the progress theSelf.currentlength=0;98Self.sumlength=0; About      -     101 }102 /*103 * Request error (failure) when called (Request timeout \ network \ No net \, usually refers to client error)104  */ the-(void) Connection: (Nsurlconnection *) connection didfailwitherror: (Nserror *) Error106 {107 }108 @end

2. Display

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