首先添加一个文本改变的触发事件
[textField addTarget:self action:@selector(textFieldDidChange:)
forControlEvents:UIControlEventEditingChanged];
然后实现该方法，做文本的限制处理
- (void)textFieldDidChange:(UITextField *)textField {
NSString *toBeString = textField.text;
// 获取高亮部分
UITextRange *selectedRange = [textField markedTextRange];
UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
// 没有高亮选择的文本，则对已输入的文本进行字数统计和限制
if (!position) {
if (toBeString.length > kMaxLength) {
NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:kMaxLength];
if (rangeIndex.length == 1) {
textField.text = [toBeString substringToIndex:kMaxLength];
}else {
NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, kMaxLength)];
textField.text = [toBeString substringWithRange:rangeRange];
}
}
}
}
这样就ok啦
