[Classroom practices and projects] IOS network ------- NSInvocationOperation and NSOper

Yesterday we introduced the use of the NSThread method, and today we will introduce the network download of NSOpreation.

I decided to present small knowledge points in a concise manner for reference.

1. Use a selector to load NSOpreation Networks

1) define the NSInvocationOperation object.

      NSInvocationOperation *operation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(downLoadImgae:) object:indexPath];

Set to thread queue

[self.queue addOperation:operation];

2) downLoadImgage Method

- (void)downLoadImgae:(NSIndexPath *)indexPath{    NSInteger row = [indexPath row];    NSString *str = [self.array objectAtIndex:row];        NSURL *url = [NSURL URLWithString:str];    NSData *imageData = [NSData dataWithContentsOfURL:url];        UIImage *image = [UIImage imageWithData:imageData];        LCMyIndetifiterCell *cell =  (LCMyIndetifiterCell *)[self.tableView cellForRowAtIndexPath:indexPath];        cell.imageView.image = image;        [cell.activityIndicatorView stopAnimating];        [cell.activityIndicatorView setHidesWhenStopped:YES];        //[self.tableView reloadData];}

2. load data using block statements

  [self.queue addOperationWithBlock:^(void){                NSInteger row = [indexPath row];        NSString *str = [self.array objectAtIndex:row];                NSURL *url = [NSURL URLWithString:str];        NSData *imageData = [NSData dataWithContentsOfURL:url];                UIImage *image = [UIImage imageWithData:imageData];                        cell.imageView.image = image;                 [cell.activityIndicatorView stopAnimating];                [cell.activityIndicatorView setHidesWhenStopped:YES];

The effect is as follows: