ios通过按钮点击异步加载图片

AsyncImageView.h:
#import <UIKit/UIKit.h>
@interface AsyncImageView : UIView
{
NSURLConnection* connection;
NSMutableData* data;
}
– (void)loadImageFromURL:(NSURL*)url;
@end
AsyncImageView.m:
#import “AsyncImageView.h”
@implementation AsyncImageView
– (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if(self) {
// Initialization code
}
returnself;
}
– (void)loadImageFromURL:(NSURL*)url {
if(connection!=nil) { [connection release]; }
if(data!=nil) { [data release]; }
NSURLRequest* request = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
}
– (void)connection:(NSURLConnection *)theConnection
didReceiveData:(NSData *)incrementalData {
if(data==nil) {
data =
[[NSMutableData alloc] initWithCapacity:2048];
}
[data appendData:incrementalData];
}
– (void)connectionDidFinishLoading:(NSURLConnection*)theConnection {
[connection release];
connection=nil;
if([[self subviews] count] > 0) {
[[[self subviews] objectAtIndex:0] removeFromSuperview];
}
UIImageView *imageView = [[[UIImageView alloc] initWithImage:[UIImage imageWithData:data]] autorelease];
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight );
[self addSubview:imageView];
imageView.frame = self.bounds;
[imageView setNeedsLayout];
[self setNeedsLayout];
[data release];
data=nil;
}
– (UIImage*) image {
UIImageView* iv = [[self subviews] objectAtIndex:0];
return[iv image];
}
– (void)dealloc {
[connection cancel];
[connection release];
[data release];
[super dealloc];
}
@end

@interface UIButton (AsyncImage)
//size by point
– (void)setImageFromURL:(NSString *)urlString adjustToSize:(CGSize)size completion:(void (^)(void))completion logo:(UIImage *)logoImage;
@end
@implementation UIButton (AsyncImage)
– (void)setImageFromURL:(NSString *)urlString adjustToSize:(CGSize)size completion:(void (^)(void))completion logo:(UIImage *)logoImage
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
UIImage *image = nil;
NSURL *url = [NSURL URLWithString:urlString];
NSData *data = [NSData dataWithContentsOfURL:url];
image = [UIImage imageWithData:data];
if (image) {
if (!CGSizeEqualToSize(size, CGSizeZero)) {
image = [UIImage imageWithCGImage:image.CGImage scale:[self scaleImage:image adjustToSize:size] orientation:image.imageOrientation];
}
if (logoImage) {
image = [self addLogoImage:logoImage toImage:image];
}
dispatch_async(dispatch_get_main_queue(), ^{
[self setImage:image forState:UIControlStateNormal];
completion();
});
}
else {
NSLog(@”async load error.”);
}
});
}
// 缩放图片以适应按钮大小
– (CGFloat)scaleImage:(UIImage *)image adjustToSize:(CGSize)size
{
CGFloat xScale = size.width / image.size.width;
CGFloat yScale = size.height / image.size.height;
return 1.0 / MIN(xScale, yScale);
}
– (UIImage *)addLogoImage:(UIImage *)logo toImage:(UIImage *)img
{
//get image width and height
CGFloat scale = [UIScreen mainScreen].scale;
int w = scale * img.size.width;
int h = scale * img.size.height;
int logoWidth = logo.scale * logo.size.width;
int logoHeight = logo.scale * logo.size.height;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
//create a graphic context with CGBitmapContextCreate
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGContextDrawImage(context, CGRectMake(w – logoWidth, 0, logoWidth, logoHeight), [logo CGImage]);
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return [UIImage imageWithCGImage:imageMasked scale:scale orientation:img.imageOrientation];
}
@end

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#import <Foundation/Foundation.h> #import "StringUtils.h" @interface ImageManager : NSObject {   NSMutableDictionary *_imageDict;   NSMutableArray *_imageArr; } @property(nonatomic, strong) NSString *httpUrl; @property(nonatomic, strong) NSMutableDictionary *imageDict; @property(nonatomic, assign) dispatch_queue_t networkQueue; + (ImageManager *) sharedInstance; - (void)asyncImage:(NSString *)imageName imageView:(UIImageView *)imageView; //插队 - (void)asyncImageInsert:(NSString *)imageName imageView:(UIImageView *)imageView insert:(BOOL)insert; //不要在下载之前的数据 - (void)asyncImageCleanOld:(NSString *)imageName imageView:(UIImageView *)imageView cleanOld:(BOOL)cleanOld; @end

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// // ImageManager.m // myb-ios // // Created by warrior gao on 13-6-5. // Copyright (c) 2013年 51myb. All rights reserved. // #import "ImageManager.h" @interface ImageManager() @end @implementation ImageManager //缓存图片的最大数量 static int counter = 0; @synthesize imageDict = _imageDict; //Singleton + (ImageManager *)sharedInstance {   static id instance;   static dispatch_once_t onceToken;   dispatch_once(&onceToken, ^{     instance = self.new;   });   return instance; } - (id)init {   if((self = [super init]))   {     self.networkQueue = dispatch_queue_create("com.warrior.network.image", nil);     _imageDict = [[NSMutableDictionary alloc] init];     _imageArr = [[NSMutableArray alloc] init];   }   return self; } - (NSString *) fileFullPath:(NSString *)fileName {   NSString *cachePath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0];      NSString *fileFullPath = [NSString stringWithFormat:@"%@/%@",cachePath,fileName];      return fileFullPath; } //不要在下载之前的数据 - (void)asyncImageCleanOld:(NSString *)imageName imageView:(UIImageView *)imageView cleanOld:(BOOL)cleanOld {   if(cleanOld)   {     [_imageArr removeAllObjects];   }      [self asyncImage:imageName imageView:imageView]; } //插队，优先 - (void)asyncImageInsert:(NSString *)imageName imageView:(UIImageView *)imageView insert:(BOOL)insert {   if([StringUtils isEmpty:imageName]){     return;   }      NSData *data = [NSData dataWithContentsOfFile:[self fileFullPath:[imageName stringByReplacingOccurrencesOfString:@"/" withString:@"-"]]];   if(data == nil){     [_imageDict setValue:imageView forKey:imageName];     if(insert)     {       [_imageArr insertObject:imageName atIndex:0];     }     else     {       [_imageArr addObject:imageName];     }          [self cacheImage];   } else {     [imageView setImage:[UIImage imageWithData:data]];   } } //正常，附加到后面 - (void)asyncImage:(NSString *)imageName imageView:(UIImageView *)imageView {   [self asyncImageInsert:imageName imageView:imageView insert:NO]; } //异步缓存图片到本地，最多有两个线程 -(void)cacheImage {   for (; counter < 2 && _imageArr.count > 0; counter++)   {     NSString *imageName = nil;     @synchronized(self){       imageName = [[_imageArr objectAtIndex:0] copy];       [_imageArr removeObjectAtIndex:0];     }          if(imageName == nil) continue;          dispatch_async(self.networkQueue, ^{              NSLog(@"Starting: %@", imageName);       UIImage *avatarImage = nil;       NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@%@",self.httpUrl, imageName]];       NSData *responseData = [NSData dataWithContentsOfURL:url];       if(responseData.length > 0)       {         [responseData writeToFile:[self fileFullPath:[imageName stringByReplacingOccurrencesOfString:@"/" withString:@"-"]] atomically:NO];         avatarImage = [UIImage imageWithData:responseData];         NSLog(@"Finishing: %@", imageName);                  if (avatarImage) {           dispatch_async(dispatch_get_main_queue(), ^{             UIImageView *imageView = [_imageDict objectForKey:imageName];             if(imageView != nil && avatarImage != nil){               [imageView setImage:avatarImage];             }                          [_imageDict removeObjectForKey:imageName];             [imageName release];           });         }       }       counter--;       [self cacheImage];     });        } } @end