objective-c - 如何解决 Range 或 index out of bounds 的运行时错误？

Question

我是 iPhone 的初学者，我得到了如下所示的运行时错误。当我在 getColor 方法中传递对象时“textView.textColor=[self getColor:appDelegate.pickcolor];” 我得到错误

由于未捕获的异常“NSRangeException”而终止应用程序，原因：“-[__NSCFConstantString substringWithRange:]: Range or index out of bounds”

- (UIColor *) getColor: (NSString *) hexColor
{
    //NSLog(@"Calling Getcolor..");
    unsigned int red, green, blue;
    NSRange range;
    range.length = 2;

    range.location = 0; 
    [[NSScanner scannerWithString:[hexColor substringWithRange:range]] scanHexInt:&red];
    //NSLog(@"\n\tRed :%d\n",red);
    range.location = 2; 
    [[NSScanner scannerWithString:[hexColor substringWithRange:range]] scanHexInt:&green];
    //NSLog(@"\n\tgreen :%d\n",green);
    range.location = 4; 
    [[NSScanner scannerWithString:[hexColor substringWithRange:range]] scanHexInt:&blue];   
    //NSLog(@"\n\tblue :%d\n",blue);
    return [UIColor colorWithRed:(float)(red/255.0f) green:(float)(green/255.0f) blue:(float)(blue/255.0f) alpha:1.0f];
}

提出任何建议和解决方案

Answer 1

也许十六进制字符串不是 6 个字符或更多？

您可以在方法开始时添加健全性检查以捕捉该场景。

- (UIColor *) getColor: (NSString *) hexColor
{
    if ([hexColor length] < 6)
        return nil;

    // ...
}