objective-c - 为什么 -[NSString 比较 :options:] return true when the strings are not equal?

Question

我正在检查一个字符串是否在数组中连续出现两次。这段代码似乎不起作用，因为它只是打印出整个数组。我错过了什么？

NSString *nameString =
    [NSString stringWithContentsOfFile:@"/usr/share/dict/words"
                              encoding:NSUTF8StringEncoding
                                 error:NULL];

NSArray *names = [nameString componentsSeparatedByString:@"\n"];

//Save last item
NSMutableString *lastOne = [NSMutableString stringWithCapacity:20];

// Go through the array one string at a time
for (NSString *n in names) {

    if ([n compare:lastOne options:NSCaseInsensitiveSearch]) {
        NSLog(@"%@", n);
    }

    [lastOne setString:n];


}

Answer 1

compare:和相关函数不返回 bool 值，它们返回 NSComparisonResult 。如果您想查看字符串是否相等，您应该使用

if ([n compare:lastOne options:NSCaseInsensitiveSearch] == NSOrderedSame)