ios通過按鈕點擊異步加載圖片

 　　本文給大家匯總了幾種IOS中實現異步加載圖片的方法，十分的簡單實用，有需要的小伙伴可以參考下。

　　比較原始的方法：

　　代碼如下:

　　AsyncImageView.h:

　　#import

　　@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

　　方法二：

　　復制代碼 代碼如下:

　　@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.");

　　}

　　});

　　}

　　// 縮放圖片以適應按鈕大小

　　- (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

　　方法三：

　　?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 #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; //插隊 - (void)asyncImageInsert:(NSString *)imageName imageView:(UIImageView *)imageView insert:(BOOL)insert; //不要在下載之前的數據 - (void)asyncImageCleanOld:(NSString *)imageName imageView:(UIImageView *)imageView cleanOld:(BOOL)cleanOld;   @end

　　實現文件：

　　?

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