限制UITextField的输入长度

如何限制UITextField的输入长度

1.给textField添加UIControlEventEditingChanged的事件处理

    [textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

2.在方法：textFieldDidChange中处理逻辑

NSString *toBeString = TextField.text;
NSString *lang = [[UIApplication sharedApplication]textInputMode].primaryLanguage;
//简体中文输入，包括简体拼音，健体五笔，简体手写
if([lang isEqualToString:@"zh-Hans"] || [lang isEqualToString:@"zh-Hant"]){ 
    UITextRange *selectedRange = [TextField markedTextRange];
    UITextPosition *position = [TextField positionFromPosition:selectedRange.start offset:0];
    if (!position){//非高亮（高亮表示只显示了汉字的拼音字母，汉字还未输入进去的状态）
        if (toBeString.length > maxLength) {
            TextField.text = [toBeString substringToIndex:maxLength];
        }
    }

}else{//中文输入法以外
    if (toBeString.length > maxLength) {
        TextField.text = [toBeString substringToIndex:maxLength];
    }
}