一直觉得自己写的不是技术，而是情怀，一个个的教程是自己这一路走来的痕迹。靠专业技能的成功是最具可复制性的，希望我的这条路能让你们少走弯路，希望我能帮你们抹去知识的蒙尘，希望我能帮你们理清知识的脉络，希望未来技术之巅上有你们也有我。

1.TextField 左边边距

self.textField.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 8, 0)];
self.textField.leftViewMode = UITextFieldViewModeAlways;

2.获取输入的值

UITextFieldDelegate
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
  NSString *newText = [textField.text stringByReplacingCharactersInRange:range withString:string];
  NSLog(@"----- %@",newText);
  return YES;
}

3.去除左右内容中的空格

 NSString *str = [self.Field.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

4.判断内容是否全部是空格

//看剩下的字符串的长度是否为零
NSString *temp = [tf.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
if ([temp length]== 0) {
}

5.只允许输入字母和数字,限制长度

image.png

#pragma mark - 输入框发生改变就触发
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
  if ([textField isEqual:self.phoneTextField]) {//手机框
    self.previousSelection = textField.selectedTextRange;
    self.previousTextFieldContent = textField.text;
      return YES;
  }else if ([textField isEqual:self.VCodeTextField]){//验证码框
      self.VCode = [textField.text stringByReplacingCharactersInRange:range withString:string];
      [self controlNextBtnByPhoneNum:self.phoneCode];
      return YES;
  }else if ([textField isEqual:self.passwordTextField]){//密码框
      //原理就是把输入的信息转换成ASCII值  查看是否符合要求
      NSUInteger lengthOfString = string.length;  //lengthOfString的值始终为1
      for (NSInteger loopIndex = 0; loopIndex < lengthOfString; loopIndex++) {
          unichar character = [string characterAtIndex:loopIndex]; //将输入的值转化为ASCII值（即内部索引值），可以参考ASCII表
          // 48-57;{0,9};65-90;{A..Z};97-122:{a..z}
          if (character < 48){ return NO; }
          if (character > 57 && character < 65){ return NO; }
          if (character > 90 && character < 97){ return NO; }
          if (character > 122){ return NO; }
      }
      NSUInteger proposedNewLength = textField.text.length - range.length + string.length;//检测总长度
      if (proposedNewLength > 16) { return NO; }//限制长度
      //上面的情况都是不合格的   返回NO
      self.pwdCode = [textField.text stringByReplacingCharactersInRange:range withString:string];
      [self controlNextBtnByPhoneNum:self.phoneCode];
      return YES;
  }else{
      return NO;
  }
}