文章结构
1.UITextField字数限制
2.UITextView字数限制
一、UITextField字数限制
[_textFieldInput addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];
_lableLimit.text = [NSString stringWithFormat:@"0/%lu",_limitLength];
#pragma mark - 字数限制
- (void)textFieldDidChange:(UITextField *)textField
{
NSInteger kMaxLength = _limitLength;
NSString *toBeString = textField.text;
NSString *lang = [[UIApplication sharedApplication]textInputMode].primaryLanguage; //ios7之前使用[UITextInputMode currentInputMode].primaryLanguage
if ([lang isEqualToString:@"zh-Hans"]) { //中文输入
UITextRange *selectedRange = [textField markedTextRange];
//获取高亮部分
UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
if (!position) {// 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 (toBeString.length > kMaxLength) {
textField.text = [toBeString substringToIndex:kMaxLength];
}
}
else{//有高亮选择的字符串，则暂不对文字进行统计和限制
}
}else{//中文输入法以外的直接对其统计限制即可，不考虑其他语种情况
if (toBeString.length > kMaxLength) {
textField.text = [toBeString substringToIndex:kMaxLength];
}
}
_lableLimit.text = [NSString stringWithFormat:@"%lu/%lu",textField.text.length,_limitLength];
}
二、UITextView字数限制与剩余字数显示
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
//不支持系统表情的输入
if ([[textView textInputMode] primaryLanguage] == nil||[[[textView textInputMode] primaryLanguage]isEqualToString:@"emoji"]) {
return NO;
}
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){
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) {
if (idx >= rg.length) {
*stop =YES;//取出所需要就break，提高效率
return ;
}
trimString = [trimString stringByAppendingString:substring];
idx++;
}];
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]];
//既然是超出部分截取了，哪一定是最大限制了。
self.lableLimit.text = [NSString stringWithFormat:@"%d/%ld",0,(long)MAX_LIMIT_NUMS];
}
return NO;
}
}
显示当前可输入字数/总字数
#pragma mark -显示当前可输入字数/总字数
- (void)textViewDidChange:(UITextView *)textView{
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
self.lableLimit.text = [NSString stringWithFormat:@"%ld/%d",MAX(0,MAX_LIMIT_NUMS - existTextNum),MAX_LIMIT_NUMS];
}
