text: //
  //  NSString+Safe.h
  //  Example
  //
  //  Created by QF on 2018/12/20.
  //  Copyright © 2018年 QF. All rights reserved.
  //
  
  #import <Foundation/Foundation.h>
  
  @interface NSString (Safe)
  
  - (NSString *)safeSubstringFromIndex:(NSUInteger)from;
  
  - (NSString *)safeSubstringToIndex:(NSUInteger)to;
  
  - (NSString *)safeSubstringWithRange:(NSRange)range;
  
  - (NSRange)safeRangeOfString:(NSString *)aString;
  
  - (NSString *)safeStringByAppendingString:(NSString *)aString;
  
  @end
  