第十课程 多线程 滚动视图

//
//  ViewController.m
//  ImageDownShow
//
//  Created by KEN on 15/7/23.
//  Copyright (c) 2015年 Tin. All rights reserved.
//

#import "ViewController.h"
#import "ImageViewController.h"
@interface ViewController ()

@end

@implementation ViewController

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if( [ segue.destinationViewController isKindOfClass:[ImageViewController class] ])
    {
        ImageViewController * ivc = ( ImageViewController *) segue.destinationViewController ;

        NSString * str = nil ;

        if( [segue.identifier isEqualToString:@"num1"])
        {
            str = @"http://f0.topit.me/0/f8/68/1122299417ae868f80o.jpg" ;
        }else
        {
            str = @"http://d.hiphotos.baidu.com/zhidao/pic/item/f3d3572c11dfa9ecd1eaad8762d0f703908fc15e.jpg" ;
        }

        ivc.imageURL = [ NSURL URLWithString: str]   ;
        ivc.title = segue.identifier ;

    }

    NSLog(@"%.2f" , 1.24444 );
}

@end

#import <UIKit/UIKit.h>

@interface ImageViewController : UIViewController

@property ( nonatomic , strong) NSURL * imageURL ;

@end

//
//  ImageViewController.m
//  ImageDownShow
//
//  Created by KEN on 15/7/23.
//  Copyright (c) 2015年 Tin. All rights reserved.
//

#import "ImageViewController.h"

@interface ImageViewController () <UIScrollViewDelegate>

@property ( nonatomic , strong) UIImageView * imageView ;
@property ( nonatomic , strong) UIImage * image ;
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *indicator;
@end

@implementation ImageViewController

-(void) setImageURL:(NSURL *)imageURL
{
    _imageURL = imageURL ;
//    self.image = [ UIImage imageWithData:[NSData dataWithContentsOfURL:self.imageURL]] ;
    [self startDownloadingImage] ;
}

-(void) startDownloadingImage
{
    self.image = nil ;
    if( self.imageURL){

        NSURLRequest * request = [ NSURLRequest requestWithURL:self.imageURL] ;
        NSURLSessionConfiguration * configuration = [ NSURLSessionConfiguration ephemeralSessionConfiguration];
        NSURLSession * session = [ NSURLSession sessionWithConfiguration:configuration] ;
        NSURLSessionDownloadTask * task = [ session downloadTaskWithRequest:request completionHandler:^(NSURL *localFile, NSURLResponse *response, NSError *error) {
            if(!error)
            {
                if( [request.URL isEqual:self.imageURL])
                {
                    UIImage * image =[ UIImage imageWithData:[NSData dataWithContentsOfURL:localFile]] ;
                    dispatch_async(dispatch_get_main_queue() , ^{
                        self.image = image ;
                    });
                }
            }
        }] ;

        [task resume];
    }

}

-(UIView * )   viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return self.imageView ;
}

-(void) viewDidLoad
{
    [super viewDidLoad];
    [self.scrollView addSubview:self.imageView] ;

    [self.indicator startAnimating];
}

-( UIImageView * ) imageView
{
    if( !_imageView) _imageView  = [[ UIImageView alloc] init ] ;
    return _imageView ;
}

-( UIImage * ) image
{
    return  self.imageView.image ;
}

-(void) setImage:(UIImage *)image
{
    self.imageView.image = image ;
    [self.imageView sizeToFit];
    self.scrollView.contentSize = self.image? self.image.size : CGSizeZero;
    [self.indicator stopAnimating];
}

-(void) setScrollView:(UIScrollView *)scrollView
{
    _scrollView = scrollView ;
    _scrollView.minimumZoomScale = 0.2 ;
    _scrollView.maximumZoomScale = 2 ;
    _scrollView.delegate = self ;

    self.scrollView.contentSize = self.image? self.image.size : CGSizeZero;
}

@end