ios通过按钮点击异步加载图片

本文给大家汇总了几种IOS中实现异步加载图片的方法，十分的简单实用，有需要的小伙伴可以参考下。  

比较原始的方法：

 

复制代码
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;