メソッドはサブクラス化することUIImageViewです。割り当てるときは、デフォルトの画像（読み込み中の画像）またはを配置しUIActivityIndicator、表示する画像を（別のスレッドで）ダウンロードし、画像がダウンロードされたら表示します。画像のダウンロードをご覧 NSURLRequestください。NSURLConnection
* 編集 *
これが私が開発したコードの例です。これを開始点として使用して、独自の読み込み画像クラスを開発できます。このクラスはNSThread、画像の読み込みに使用することで改善できます。
// ImageLoader.h
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
/**
* @brief Class that loads an UIImage from a server
* @author Nicolas
*/
@interface ImageLoader : UIView
{
@private
NSURLConnection *connection;
NSMutableData *data;
NSString *path;
UIActivityIndicatorView *loading;
UIImageView *imageView;
}
@property (nonatomic, retain) UIActivityIndicatorView *loading;
@property (nonatomic, retain) NSURLConnection *connection;
@property (nonatomic, retain) NSMutableData *data;
@property (nonatomic, retain) NSString *path;
@property (nonatomic, retain) UIImageView *imageView;
/**
* Load an image from a server an display it
* @param URL URL to get the image
* @param chemin path to save the image
* @author Nicolas
*/
- (void)loadImageFromUrl:(NSString *)URL forPath:(NSString *)chemin;
@end
// ImageLoader.m
#import "ImageLoader.h"
@implementation ImageLoader
@synthesize path, connection, data, loading, imageView;
- (id)init
{
self = [super init];
[self setUserInteractionEnabled:YES];
return self;
}
- (void)loadImageFromUrl:(NSString *)URL forPath:(NSString *)chemin
{
//if (connection != nil) [connection release];
//if (data != nil) [data release];
//if (path != nil) [path release];
self.path = chemin;
if ([[NSFileManager defaultManager] fileExistsAtPath:chemin])
{
if (imageView != nil)
{
[imageView removeFromSuperview];
[imageView release];
}
imageView = [[UIImageView alloc] initWithFrame:self.bounds];
imageView.image = [UIImage imageWithContentsOfFile:chemin];
[self addSubview:imageView];
}
else
{
loading = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0, 0, 20.0f, 20.0f)];
loading.center = CGPointMake(self.frame.size.width/2, self.frame.size.height/2);
[loading setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
[loading startAnimating];
[self addSubview:loading];
NSURL *myURL = [NSURL URLWithString:[URL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSURLRequest *request = [NSURLRequest requestWithURL:myURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0f];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
}
}
#pragma mark -
#pragma mark NSURLConnection protocol
- (void)connection:(NSURLConnection *)_connection didReceiveData:(NSData *)_data
{
if (data == nil)
{
data = [[NSMutableData alloc] initWithCapacity:2048];
}
[data appendData:_data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)_connection
{
[data writeToFile:self.path atomically:YES];
if (imageView != nil)
{
[imageView removeFromSuperview];
[imageView release];
}
imageView = [[UIImageView alloc] initWithImage:[UIImage imageWithData:data]];
imageView.frame = self.bounds;
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
[loading stopAnimating];
[loading setHidden:YES];
[self addSubview:imageView];
}
- (void)connection:(NSURLConnection *)_connection didFailWithError:(NSError *)error
{
[loading stopAnimating];
[loading release];
}
#pragma mark - Memory management
- (void)dealloc
{
[connection cancel];
[connection release];
[imageView release];
[path release];
[data release];
[super dealloc];
}
@end