I've install iOS11 beta5 and catch some problems. I override drawTextInRect method for my custom UITextField, but it is never called. 
Note: yes, i've already seen this answer, but it is works fine on 10.3.
Code sample to reproduce that behavior:
#import <UIKit/UIKit.h>  
@interface MYCustomTextField : UITextField  
@end  
@implementation MYCustomTextField  
-(void)drawTextInRect:(CGRect)rect {  
  [super drawTextInRect:rect];  
  NSLog(@"drawTextInRect calling");  
}  
@end  
I've also created a new thread on Apple's developer forum.