给UIView添加扩展方法：

// 截屏
- (UIImage *)captureScreenshot {UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);// IOS7及其后续版本if ([self respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]) {NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]];[invocation setTarget:self];[invocation setSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)];CGRect arg2 = self.bounds;BOOL arg3 = YES;[invocation setArgument:&arg2 atIndex:2];[invocation setArgument:&arg3 atIndex:3];[invocation invoke];} else { // IOS7之前的版本[self.layer renderInContext:UIGraphicsGetCurrentContext()];}UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();return screenshot;
}