ios 图片操作

http://stackoverflow.com/questions/3837115/display-image-from-url-retrieved-from-alasset-in-iphone  　　display image from URL retrieved from ALAsset in iPhone

http://stackoverflow.com/questions/1282830/uiimagepickercontroller-uiimage-memory-and-more UIImagePickerController, UIImage, Memory and More? [closed]

http://blog.csdn.net/sdhjob/article/details/6942793  IPad开发拍照并将图片保存到照片库中

http://stackoverflow.com/questions/1238838/uiimagepickercontroller-and-extracting-exif-data-from-existing-photos  UIImagePickerController and extracting EXIF data from existing photos

1.把图片写入文件

- (BOOL)writeImage:(UIImage*)image toFileAtPath:(NSString*)aPath
{
    if ((image == nil) || (aPath == nil) || ([aPath isEqualToString:@""]))
        return NO;
    @try
    {
        NSData *imageData = nil;
        
        NSString *ext = [aPath pathExtension];
        
        if ([ext isEqualToString:@"png"])
        {
            imageData = UIImagePNGRepresentation(image);
            NSLog(@"png");
        }
        else
        {
            NSLog(@"jpg");
            // the rest, we write to jpeg
            // 0. best, 1. lost. about compress.
            imageData = UIImageJPEGRepresentation(image, 0);
        }
        if ((imageData == nil) || ([imageData length] <= 0))
            return NO;
        [imageData writeToFile:aPath atomically:YES];
        return YES;
    }
    @catch (NSException *e) 
    {
        NSLog(@"create thumbnail exception.");
    }
    return NO;
}

2.从文件加载图片

-(UIImage *)loadImageFromFile:(NSString *) aPath;
{
    UIImage *im=[[UIImage alloc] initWithContentsOfFile:[self dataFilePath:aPath]];
    if (im==nil)
        NSLog(@"nil %@",[self dataFilePath:aPath]);
    return im;
}

3. uiimage大小

image.size.width,image.size.height

4.点击图片响应事件

    resizedImageView.userInteractionEnabled = YES;
    UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(photoTapped)];
    [resizedImageView addGestureRecognizer:singleTap];//点击图片事件
    NSLog(@"haha");
    [self.view addSubview:resizedImageView];//加载图片