gistfile1.c

[subview updateFrame:^(CGPoint *origin, CGSize *size) {
    origin->y = floor((CGRectGetHeight(self.bounds) - SubviewHeight)/2);
}];

UIView+ASEAddittions.h

@interface UIView (Bryan)

- (void)updateFrame:(void (^)(CGPoint *origin, CGSize *size))block;

@end

@implementation UIView (Bryan)

- (void)updateFrame:(void (^)(CGPoint *origin, CGSize *size))block {
    CGRect frame = self.frame;
    CGPoint origin = frame.origin;
    CGSize size = frame.size;
    
    block(&origin, &size);
    
    frame.origin = origin;
    frame.size = size;
    self.frame = frame;
}

@end