Load the network picture in GCD Way (main line loads download image + Class extension mode)

Load the network picture in GCD Way (main line loads download image + Class extension mode)

Two ways to implement the Network load picture

Method 1: effect: Load the background color gray first, load the picture after two seconds

-(void) Viewdidload {

[super viewdidload];

self. View. BackgroundColor=[uicolor graycolor];

// refresh UI (Refresh ui!!! in the main thread) )--- general method

dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default ,  0 ), ^{

nsstring * path=@ "http://www.sinaimg.cn/dy/slidenews/4_img/2015_12/704_1579347_ 398766.jpg ";

nsdata * data=[nsdata datawithcontentsofurl: [Nsurl urlwithstring:p Ath]];

UIImage * image=[UIImage imagewithdata:d ATA];

NSLog(@ "%@", [nsthread currentthread]);

// return to main thread

dispatch_sync(dispatch_get_main_queue(), ^{

[nsthread sleepfortimeinterval:2];

NSLog     (@ "%@", [nsthread currentthread]); // Test Code --- See if the place goes back to the main thread.

Self. ImageView.   image=image; // to be Image Assign Value

});

});

}

Method 2: Class extension (encapsulation Class)

#import "Uiimageview+loadimage.h"

@implementation Uiimageview (LoadImage)

-(void) Loadimagewithpath: (nsstring *) path defaultimage: (nsstring *) Dafaultpath

{

dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default ,  0 ), ^{

// cannot assign a value directly to an external variable within the block , you need to turn the type

__block nsstring * str = path;

if (path==Nil)

{

Str=dafaultpath;

}

Else

{

nsdata * data=[nsdata datawithcontentsofurl: [nsurl urlwithstring:p Ath]];

UIImage * image=[UIImage imagewithdata:d ATA];

[nsthread sleepfortimeinterval:2];

// return to main thread

dispatch_sync(dispatch_get_main_queue(), ^{

Self. image=image;

});

}

});

}

@end

Import #import "Uiimageview+loadimage.h" in the viewcontroller.m file and call the class extension method

@implementation Viewcontroller

-(void) Viewdidload {

[super viewdidload];

self. View. BackgroundColor=[uicolor graycolor];

      nsstring  * path= @ "http://www.sinaimg.cn/dy/slidenews/4_img/2015_12/704_ 1579347_398766.jpg "

[self. ImageView loadimagewithpath:p ath defaultimage:nil];  

}

In terms of the comparison between the two methods, or the method of class extension is better, if you encounter a problem that requires the network to load pictures, you can take the encapsulated class directly to use.

Load the network picture in GCD Way (main line loads download image + Class extension mode)