为什么 - [NSString compare:options:]在字符串不相等时返回true？

Question

我正在检查一个字符串是否在一个数组中连续出现两次.这段代码似乎不起作用,因为它只打印出整个数组.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:和相关的功能不返回布尔值,他们返回一个NSComparisonResult.如果你想看一个字符串是否相等,你应该使用

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