iPhone 应用里实现截屏功能的代码

iPhone 用户同时按下 Home 和锁屏键就能截屏，但在应用里总不能跳出一行字让用户自己按截屏键。CocoaChina 会员 “bobgreen” 分享的这段代码能实现程序内截屏功能，支持 iPhone 4 Retina 高分屏。

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            //支持retina高分的关键            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 {                NSLog(@"Failed!");            }        }    }