iphone - '>' 的左操作数是垃圾值

Question

当我构建并分析我的应用程序时，我收到以下内存警告

"The left operand of '>' is a garbage value" at this line isTrue = (newLength > 20) ? NO : YES;

这里有什么问题。感谢您的帮助

 (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSUInteger newLength;
    BOOL isTrue;
    if(textField == txtFirstName){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue = (newLength > 20) ? NO : YES;
    }
    if(textField == txtLastName){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue = (newLength > 20) ? NO : YES;
    }
    if(textField == txtEmail){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue =  (newLength > 100) ? NO : YES;
    }
    if(textField == txtCompanyName){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue =  (newLength > 30) ? NO : YES;
    }
    if(textField == txtPassword){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue =  (newLength > 30) ? NO : YES;
    }
    if(textField == txtRe_EnterPassword){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue =  (newLength > 30) ? NO : YES;
    }
    if(textField == txtZipCode){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue =  (newLength > 20) ? NO : YES;
    }
    if(textField == txtCountry){
        newLength = [textField.text length] + [string length] - range.length;
        //isTrue =  (newLength > 30) ? NO : YES;
    }
    isTrue = (newLength > 20) ? NO : YES;

    return isTrue;
}

Answer 1

当所有的 if 条件都失败时，问题就会出现，即。如果 textField 不是您期望的集合之一。

在这种情况下，newLength 永远不会被赋值，而是一个随机的垃圾值。 虽然这可能“永远不会发生”，但静态分析器并不知道这一点。

您应该将 newLength 初始化为默认值，可能为零。