截取当前屏幕

#import <QuartzCore/QuartzCore.h>@property (retain, nonatomic) IBOutlet UIImageView *imageView;-(UIImage*)getShot{    UIGraphicsBeginImageContext(CGSizeMake(320, 460));    [imageView.layer renderInContext:UIGraphicsGetCurrentContext()];    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    return viewImage;}