限制输入到UITextField的字符数

Question

我有一个UITextField，我限制输入超过2位数。现在，它工作正常，但当我点击文本字段&选择所有内容&然后键入它不允许我覆盖现有的2位数字。

关于如何在这里使用'selectedTextRange'属性的任何线索？

- (BOOL)cell:(RunnerTableViewCell *)iCell shouldChangeCharactersInRange:(NSRange)iRange replacementString:(NSString *)iString { 
    self.navigationItem.rightBarButtonItem.enabled = YES; 
    NSCharacterSet *anUnacceptedInput = [[NSCharacterSet decimalDigitCharacterSet] invertedSet]; 
    int aCharacterUpperLimit = 2; 
    BOOL aReturnValue = YES; 

    NSInteger aTotalLength = iCell.inputField.text.length + [iString length]; 
    NSLog(@"iString=%@ aTotalLength=%d",iString,aTotalLength); 
    if ([[iString componentsSeparatedByCharactersInSet:anUnacceptedInput] count] > 1 || (aTotalLength > aCharacterUpperLimit && ![iString isEqualToString:kRunnerEmptyString]) || [iString length] > aCharacterUpperLimit) { 
     aReturnValue = NO; 
    } 
    return aReturnValue; 
} 

Answer 1

试试这个：

NSInteger aTotalLength = iCell.inputField.text.length + [iString length] - iRange.length;