Asynchronous download of images

Download Image////////

Method one (violent and effective, must be downloaded before entering the page) sync

Nsurl *url = [Nsurl urlwithstring:@ "Http://cc.cocimg.com/bbs/attachment/upload/07/128707.png"];

UIImage *IMGA = [[UIImage alloc] Initwithdata:[nsdata Datawithcontentsofurl:url]];

Img1.image=imga;

Method Two (need to wait for the download to display, but can still enter the page) async

NSString *[email protected] "HTTP://TP1.SINAIMG.CN/2122519000/50/5620445947/1";

Uiimagefromurl ([Nsurl Urlwithstring:url2], ^ (UIImage * image)

{

Img2.image=image;

NSLog (@ "----%@", image);

}, ^ (void) {

NSLog (@ "error!");

} );

The following is a//////////of reading and writing documents

UIImage *bear=[uiimage imagenamed:@ "Image.png"];

Document creates a directory search path in a list. Get the Documents folder for your application

Nsarray *patharray = Nssearchpathfordirectoriesindomains (Nsdocumentdirectory,nsuserdomainmask, YES);

NSString *paths = [Patharray lastobject];

NSString *uniquepath = [[Nshomedirectory () stringbyappendingpathcomponent:@ "Documents"]

stringbyappendingpathcomponent:@ "Image.png"];

/* Write picture */

Get a name for the file.

NSString *uniquepath=[[paths stringbyappendingpathcomponent:@ "image"] stringbyappendingpathcomponent:@ " Image.png "];

Write the picture to the documents file

Get the Image object in PNG format

[Uiimagepngrepresentation (Bear) Writetofile:uniquepath Atomically:yes];

/* Read in Picture */

Because it's a path, it's loaded into a data object.

NSData *data=[nsdata Datawithcontentsoffile:uniquepath];

Just read the picture.

Img3.image=[uiimage Imagewithdata:data];

[Super Viewdidload];

}

-(void) didreceivememorywarning

{

[Super didreceivememorywarning];

}

-(void) Dealloc {

[IMG1 release];

[Img2 release];

[IMG3 release];

[Super Dealloc];

}

#pragma mark-Method two

//

void Uiimagefromurl (Nsurl * URL, Void (^imageblock) (UIImage * image), void (^errorblock) (void))

{

Presents an asynchronous execution block in the dispatch queue and returns immediately.

Dispatch_async (Dispatch_get_global_queue (dispatch_queue_priority_default, 0), ^ (void)

{

NSData * data = [[[NSData alloc] initwithcontentsofurl:url] autorelease];

UIImage * image = [[[UIImage alloc] initwithdata:data] autorelease];

Returns the serial dispatch queue associated with the main thread of the application.

Dispatch_async (Dispatch_get_main_queue (), ^ (void) {

if (image = nil)

{

Imageblock (image);

} else {

Errorblock ();

}

});

});

}

@end

Asynchronous download of images