#pragma mark-- UITextViewDelegate

最新推荐文章于 2019-12-13 14:22:10 发布

转载最新推荐文章于 2019-12-13 14:22:10 发布 · 244 阅读

文章标签：

#textview

iOS 专栏收录该内容

13 篇文章

订阅专栏

本文介绍如何在 iOS 开发中使用 UITextView 实现文本输入长度限制，并通过代理方法实现文本视图的高度动态调整，确保良好的用户体验。

pragma mark– UITextViewDelegate

(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range
replacementText:(NSString *)text
{
//对于退格删除键开放限制
if (text.length == 0){
return YES;
}
UITextRange *selectedRange = [textView markedTextRange];
//获取高亮部分
UITextPosition *pos = [textView positionFromPosition:selectedRange.start offset:0];
//获取高亮部分内容
//NSString * selectedtext = [textView textInRange:selectedRange];
//如果有高亮且当前字数开始位置小于最大限制时允许输入
if (selectedRange && pos) {
NSInteger startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.start];
NSInteger endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.end];
NSRange offsetRange = NSMakeRange(startOffset, endOffset - startOffset);

if (offsetRange.location < MAX_LIMIT_NUMS) {
    return YES;
}
else
{
    return NO;
}

}
NSString *comcatstr = [textView.text stringByReplacingCharactersInRange:range withString:text];

NSInteger caninputlen = MAX_LIMIT_NUMS - comcatstr.length;

if (caninputlen >= 0)
{
//加入动态计算高度
CGSize size = [self getStringRectInTextView:comcatstr InTextView:textView];
// CGRect frame = textView.frame;
// frame.size.height = size.height;
// textView.frame = frame;
[textView mas_updateConstraints:^(MASConstraintMaker *make) {
make.height.mas_equalTo(size.height);
}];
return YES;
}
else
{
NSInteger len = text.length + caninputlen;
//防止当text.length + caninputlen < 0时，使得rg.length为一个非法最大正数出错
NSRange rg = {0,MAX(len,0)};

if (rg.length > 0)
{
    NSString *s = @"";
    //判断是否只普通的字符或asc码(对于中文和表情返回NO)
    BOOL asc = [text canBeConvertedToEncoding:NSASCIIStringEncoding];
    if (asc) {
        s = [text substringWithRange:rg];//因为是ascii码直接取就可以了不会错
    }
    else
    {
        __block NSInteger idx = 0;
        __block NSString  *trimString = @"";//截取出的字串
        //使用字符串遍历，这个方法能准确知道每个emoji是占一个unicode还是两个
        [text enumerateSubstringsInRange:NSMakeRange(0, [text length])
                                 options:NSStringEnumerationByComposedCharacterSequences
                              usingBlock: ^(NSString* substring, NSRange substringRange, NSRange enclosingRange, BOOL* stop) {

                                  NSInteger steplen = substring.length;
                                  if (idx >= rg.length) {
                                      *stop = YES; //取出所需要就break，提高效率
                                      return ;
                                  }

                                  trimString = [trimString stringByAppendingString:substring];

                                  idx = idx + steplen;
                              }];

        s = trimString;
    }
    //rang是指从当前光标处进行替换处理(注意如果执行此句后面返回的是YES会触发didchange事件)
    [textView setText:[textView.text stringByReplacingCharactersInRange:range withString:s]];

    //由于后面反回的是NO不触发didchange
    [self refreshTextViewSize:textView];
    //既然是超出部分截取了，哪一定是最大限制了。
    // 显示多少个字

// self.lbNums.text = [NSString stringWithFormat:@”%d/%ld”,0,(long)MAX_LIMIT_NUMS];
}
return NO;
}
}

(void)textViewDidChange:(UITextView *)textView
{
self.adressCell.valueTextField.text = textView.text; // 触发kvo
UITextRange *selectedRange = [textView markedTextRange];
//获取高亮部分
UITextPosition *pos = [textView positionFromPosition:selectedRange.start offset:0];

//如果在变化中是高亮部分在变，就不要计算字符了
if (selectedRange && pos) {
return;
}

NSString *nsTextContent = textView.text;
NSInteger existTextNum = nsTextContent.length;

if (existTextNum > MAX_LIMIT_NUMS)
{
//截取到最大位置的字符(由于超出截部分在should时被处理了所在这里这了提高效率不再判断)
NSString *s = [nsTextContent substringToIndex:MAX_LIMIT_NUMS];
```
[textView setText:s];
```
}

//不让显示负数口口日
// self.lbNums.text = [NSString stringWithFormat:@”%ld/%d”,MAX(0,MAX_LIMIT_NUMS - existTextNum),MAX_LIMIT_NUMS];

[self refreshTextViewSize:textView];
}
-(void)textViewDidEndEditing:(UITextView *)textView{
self.adressCell.valueTextField.text = textView.text; // 触发kvo
[self getStoreAndStoreSiteWithDetailSite:textView.text];
}
(void)refreshTextViewSize:(UITextView *)textView
{
CGSize size = [textView sizeThatFits:CGSizeMake(CGRectGetWidth(textView.frame), MAXFLOAT)];
// CGRect frame = textView.frame;
// frame.size.height = size.height;
// textView.frame = frame;
[textView mas_updateConstraints:^(MASConstraintMaker *make) {
make.height.mas_equalTo(size.height);
}];
}
(CGSize)getStringRectInTextView:(NSString )string InTextView:(UITextView )textView;
{
//
// NSLog(@”行高＝ %f container = %@,xxx = %f”,self.textview.font.lineHeight,self.textview.textContainer,self.textview.textContainer.lineFragmentPadding);
//
//实际textView显示时我们设定的宽
CGFloat contentWidth = CGRectGetWidth(textView.frame);
//但事实上内容需要除去显示的边框值
CGFloat broadWith = (textView.contentInset.left + textView.contentInset.right
+ textView.textContainerInset.left
+ textView.textContainerInset.right
+ textView.textContainer.lineFragmentPadding/左边距/
+ textView.textContainer.lineFragmentPadding/右边距/);

CGFloat broadHeight = (textView.contentInset.top
+ textView.contentInset.bottom
+ textView.textContainerInset.top
+ textView.textContainerInset.bottom);//+self.textview.textContainer.lineFragmentPadding/top//+theTextView.textContainer.lineFragmentPadding//there is no bottom padding/);

//由于求的是普通字符串产生的Rect来适应textView的宽
contentWidth -= broadWith;

CGSize InSize = CGSizeMake(contentWidth, MAXFLOAT);

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];
paragraphStyle.lineBreakMode = textView.textContainer.lineBreakMode;
NSDictionary *dic = @{NSFontAttributeName:textView.font, NSParagraphStyleAttributeName:[paragraphStyle copy]};

CGSize calculatedSize = [string boundingRectWithSize:InSize options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:dic context:nil].size;

CGSize adjustedSize = CGSizeMake(ceilf(calculatedSize.width),calculatedSize.height + broadHeight);//ceilf(calculatedSize.height)
return adjustedSize;
}