值得收藏的iOS开发常用代码块

2020-01-18 16:10:45丽君

取消UICollectionView的隐式动画


//方法一
[UIView performWithoutAnimation:^{
  [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
}];

//方法二
[UIView animateWithDuration:0 animations:^{
  [collectionView performBatchUpdates:^{
    [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
  } completion:nil];
}];

//方法三
[UIView setAnimationsEnabled:NO];
[self.trackPanel performBatchUpdates:^{
  [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
} completion:^(BOOL finished) {
  [UIView setAnimationsEnabled:YES];
}];

判断邮箱格式是否正确的代码


-(BOOL)isValidateEmail:(NSString *)email

  {

  NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,4}";

  NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES%@",emailRegex];

  return [emailTest evaluateWithObject:email];

  }

iOS中UITextField的字数限制


//在viewDidLoad中注册<UITextFieldTextDidChangeNotification>通知
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(textFiledEditChanged:) 
     name:@"UITextFieldTextDidChangeNotification" object:myTextField];
//实现监听方法
#pragma mark - Notification Method
-(void)textFieldEditChanged:(NSNotification *)obj
{
  UITextField *textField = (UITextField *)obj.object;
  NSString *toBeString = textField.text;

  //获取高亮部分
  UITextRange *selectedRange = [textField markedTextRange];
  UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];

  // 没有高亮选择的字,则对已输入的文字进行字数统计和限制
  if (!position)
  {
    if (toBeString.length > MAX_STARWORDS_LENGTH)
    {
      NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:MAX_STARWORDS_LENGTH];
      if (rangeIndex.length == 1)
      {
        textField.text = [toBeString substringToIndex:MAX_STARWORDS_LENGTH];
      }
      else
      {
        NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, MAX_STARWORDS_LENGTH)];
        textField.text = [toBeString substringWithRange:rangeRange];
      }
    }
  }
}

小伙伴们,今天就分享到这里,下期更精彩!


注:相关教程知识阅读请移步到IOS开发频道。