// 限制textfield输入字数
- (NSString *)limitTextFieldNum:(UITextField *)textField withNum:(NSInteger)maxNum{
NSInteger kMaxLength = maxNum;
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
if (toBeString.length > kMaxLength) {
textField.text = [toBeString substringToIndex:kMaxLength];
}
}
}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];
}
}
return textField.text;
}