一个按钮点击，复制label上面的文字

UIPasteboard *pab = [UIPasteboard generalPasteboard];

NSString *string = @"测试";

[pab setString:string];

if (pab == nil) {

[MBProgressHUD showError:@"复制失败"];

}else

{

[MBProgressHUD showSuccess:@"已复制"];

}