iOS uiimageview loading network pictures asynchronously

Method 1: Load the network picture synchronously in the UI thread

1. Uiimageview *headview = [[Uiimageview alloc] Initwithframe:cgrectmake (0, 0, 40, 40)];
3. Nsurl *photourl = [Nsurl urlwithstring:@"Http://www.exampleforphoto.com/pabb/test32.png"];
4. URL requests are actually made in the UI main thread
5. UIImage *images = [UIImage imagewithdata:[nsdata datawithcontentsofurl:photourl]; //Get uiimage via network URL
6. Headview.image = images;

This is the simplest, but because it is loaded in the main thread, it blocks the main thread of the UI. So you can try Nsoperationqueue, a nsoperationqueue operation queue, which is equivalent to a thread manager, not a thread. Because you can set the number of threads that can run in parallel in this thread manager, and so on.

Method 2: Use Nsoperationqueue to load asynchronously

2. Here's how to use Nsoperationqueue to implement a loads-load image:
4. -(void) Viewdidload
6. {
8. [Super Viewdidload];
12. Nsoperationqueue *operationqueue = [[Nsoperationqueue alloc] init];
16. Self.imageview = [[[Uiimageview Alloc] Initwithframe:cgrectmake ((+), [[]] autorelease];
18. [Self.imageview Setbackgroundcolor:[uicolor Graycolor];
20. [Self.view AddSubview:self.imageview];
24. Nsinvocationoperation *op = [[Nsinvocationoperation alloc] initwithtarget:self selector: @selector (downloadimage) Object:nil];
26. [Operationqueue Addoperation:op];
28. }
32. -(void) Downloadimage
34. {
36. Nsurl *imageurl = [Nsurl Urlwithstring:headimage_url];
38. UIImage *image = [UIImage imagewithdata:[nsdata datawithcontentsofurl:imageurl];
40. Self.imageview.image = image;
42. }

However, this design, though asynchronous, does not have a cached picture. Reloading and re-reading pictures from the network, repeating the request, is not scientific, so you can consider the first request to save the picture.

iOS uiimageview loading network pictures asynchronously