iOS: recursively find subview matching condition

+ (UIView *)viewOfClass:(NSString *)classStr insideView:(UIView *)view withCondition:(ViewTestBlock)viewTestBlock {
    return [self viewOfClass:classStr insideView:view shouldMatchClassStrictly:NO withCondition:viewTestBlock];
}

+ (UIView *)viewOfClass:(NSString *)classStr insideView:(UIView *)view shouldMatchClassStrictly:(BOOL)shouldMatchClassStrictly withCondition:(ViewTestBlock)viewTestBlock {
    Class class = NSClassFromString(classStr);
    for (UIView *v in view.subviews) {
        UIView *result;
        if (shouldMatchClassStrictly ? [v isMemberOfClass:class] : [v isKindOfClass:class]) {
            if (!viewTestBlock || viewTestBlock(v)) {
                result = v;
            }
        }
        else {
            result = [self viewOfClass:classStr insideView:v shouldMatchClassStrictly:shouldMatchClassStrictly withCondition:viewTestBlock];
        }
        if (result) {
            return result;
        }
    }
    return nil;
}