Objective C: Method Swizzling of UITableViewDelegate method - ios

Question

I am using method swizzling in my project using (JRSwizzle). I have implemented swizzling for "UIViewController" and "UIButton". It works fine.
But i am having trouble in swizzling a UITableViewDelegate method "willDisplayCell". Can anyone provide me a working sample of this?
As i understand,
Step 1: We need to create a category of the class we want to swizzle.
Example: UIViewController+Swizzle or UIButton+Swizzle
Step 2: Implement the +load and swizzleMethod like below
+ (void)load
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
NSError *error;
BOOL result = [[self class] jr_swizzleMethod:#selector(viewWillAppear:) withMethod:#selector(xxx_viewWillAppear) error:&error];
if (!result || error) {
NSLog(#"Can't swizzle methods - %#", [error description]);
}
});
}
- (void)xxx_viewWillAppear
{
[self xxx_viewWillAppear]; // this will call viewWillAppear implementation, because we have exchanged them.
//TODO: add customer code here. This code will work for every ViewController
NSLog(#"xxx_viewWillAppear for - %#", NSStringFromClass(self.class));
}
But, if i create a category for "UITableViewController" and do the method swizzle like below,
+ (void)load
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
NSError *error;
BOOL result = [[self class] jr_swizzleMethod:#selector(willDisplayCell:) withMethod:#selector(xxx_willDisplayCell) error:&error];
if (!result || error) {
NSLog(#"Can't swizzle methods - %#", [error description]);
}
});
}
- (void)xxx_willDisplayCell
{
}
The BOOL result is always "NO" and says something like "method not found or available". That may be because "willDisplayCell" is a delegate method of "UITableViewDelegate" and not "UITableViewController"
That being the case, i cannot do step 1 above. That is, i cannot create a category for "UITableViewDelegate". XCode doesn't even allow that.
And this is were i am stuck. Completely clueless on how to do this.
Can someone help here!!