给界面上任何控件截图并保存为PNG的方法

 UIView *view = [[[[[UIApplication sharedApplication] windows] objectAtIndex:1] subviews] lastObject];//获得某个window的某个subView
 
    NSInteger index = 0;//用来给保存的png命名
    for (UIView *subView in [view subviews]) {//遍历这个view的subViews
        if ([subView isKindOfClass:NSClassFromString(@"UIImageView")] || [subView isKindOfClass:NSClassFromString(@"UIThreePartButton")]) {//找到自己需要的subView
           
            if(UIGraphicsBeginImageContextWithOptions != NULL)
            {
                UIGraphicsBeginImageContextWithOptions(subView.frame.size, NO, 0.0);
            } else {
                UIGraphicsBeginImageContext(subView.frame.size);
            }            
 
            //获取图像
            [subView.layer renderInContext:UIGraphicsGetCurrentContext()];
            UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
 
            //保存图像
            NSString *path = [NSHomeDirectory() stringByAppendingFormat:@"/%d.png",index];
            if ([UIImagePNGRepresentation(image) writeToFile:path atomically:YES]) {
                index += 1;
                NSLog(@"Succeeded!");
            }
            else {

附：截屏代码

 UIGraphicsBeginImageContext(self.view.bounds.size);

 [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];

 UIImage *image= UIGraphicsGetImageFromCurrentImageContext();

 UIGraphicsEndImageContext();

 UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);

    在91助手上常见iPhone屏幕截图的功能，于是就开始想办法，看能不能手动把屏幕截图做出来。下面这个函数的代码，就是根据UIView上的 显示内容生成一张屏幕截图。值得注意的是，其中引用了Quartz2D中的函数，所以要使用的话要在文件头部增加一个引用。
#import QuartzCore/QuartzCore.h
-(UIImage *)getImageFromView:(UIView *)orgView{
UIGraphicsBeginImageContext(orgView.bounds.size); 
[orgView.layer renderInContext:UIGraphicsGetCurrentContext()]; 
UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); return image;
}