Every IDE I have ever used (besides XCode) has a dead-simple way for you to find the matching brace in a piece of code. You usually select one brace and then the other one is highlighted.
XCode does this but only for like 1/100000 of a second, and it does not help when the brace is off the screen, which is the only time you really need this function.
Is there a way to do it? I know there used to be that way of folding up the entire scope so that it disappeared, but I always hated that, it was confusing and alarming, and besides I don't even see it anymore.
Can somebody please let me know how to do it? I am sure there is a way and I don't see it -- why don't they just do it like everyone else does?
Xcode highlights an opening delimiter (brace, bracket, parenthesis) when you move the cursor left-to-right over the matching closing delimiter. The highlight animation lasts about 1 second total, which is plenty in the case where you need a hint (and as you say the other delimiter is nearby).
If you need a more persistent indication, you can double-click either the opening or the closing delmiter, and Xcode will select both delimiters and their contents. (You can also use this, for example, to get quickly to one delimiter from another, even if they're far apart — double-click the delimiter you can see, use the left or right arrow to get the the other end of the selection.)
Presumably, they don't "just do it like everyone else does" because Xcode has done it this way for many, many years and people who actually use Xcode are used to it and would prefer that it wasn't arbitrarily changed on them.
C# (for example) has a non-selection highlighting mechanism that's useful, but it also results in your source code lighting up, sometimes, in a chaos of garish colors. So it's pretty much a personal choice which unpleasant side effects you prefer.
Still, this is the sort of thing you should submit a bug report about, since that's how the popularity contest for new features works. If enough people ask for it, Apple may well change or enhance the current behavior.