设置UITextField最大长度 [英] Set UITextField Maximum Length

问题描述

有没有办法在UITextField上设置最大长度？

Is there any way to set the maximum length on a UITextField?

类似于HTML输入字段中的MAXLENGTH属性。

Something like the MAXLENGTH attribute in HTML input fields.

推荐答案

这适用于退格和复制&粘贴：

This works correctly with backspace and copy & paste:

#define MAXLENGTH 10

- (BOOL)textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    NSUInteger oldLength = [textField.text length];
    NSUInteger replacementLength = [string length];
    NSUInteger rangeLength = range.length;

    NSUInteger newLength = oldLength - rangeLength + replacementLength;

    BOOL returnKey = [string rangeOfString: @"\n"].location != NSNotFound;

    return newLength <= MAXLENGTH || returnKey;
}

更新：已更新甚至接受返回键在MAXLENGTH时。谢谢Rogers先生！

UPDATE: Updated to accept the return key even when at MAXLENGTH. Thanks Mr Rogers!

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