NSString包含字符串崩溃 [英] NSString containsString crashes

问题描述

我正在尝试根据其中一个字符串字段过滤数组。

I'm trying to filter an array according to one of it's string fields.

nameLower和filterLower里面都有NSString值，但我一直得到：

Both nameLower and filterLower has NSString value inside, and yet i keep getting:

__NSCFString containsString:]: unrecognized selector sent to instance 0x7f876b79e160

-(void) filterFriendsArray:(NSString*)filter {
    [_filteredFriendsArray removeAllObjects];
    for (FacebookUser* user in _friendsArray)
    {
        NSString* nameLower = [user.user.name lowercaseString];
        NSString* filterLower = [filter lowercaseString];
        if ([nameLower containsString:filterLower])
            [_filteredFriendsArray addObject:user];
    }
    _displayedFriendsArray = _filteredFriendsArray;
}

推荐答案

如果你想要你的代码在iOS 7以及iOS 8上工作时，您应该使用其中一个rangeOfString调用。基本上，如果返回的范围的长度为零，则子字符串不存在。

If you want your code to work on iOS 7 as well as iOS 8 you should use one of the rangeOfString calls instead. Basically if the range returned has a length of zero, the substring is not there.

/* These methods return length==0 if the target string is not found. So, to check for containment: ([str rangeOfString:@"target"].length > 0).  Note that the length of the range returned by these methods might be different than the length of the target string, due composed characters and such.
*/
- (NSRange)rangeOfString:(NSString *)aString;
- (NSRange)rangeOfString:(NSString *)aString options:(NSStringCompareOptions)mask;
- (NSRange)rangeOfString:(NSString *)aString options:(NSStringCompareOptions)mask range:(NSRange)searchRange;
- (NSRange)rangeOfString:(NSString *)aString options:(NSStringCompareOptions)mask range:(NSRange)searchRange locale:(NSLocale *)locale NS_AVAILABLE(10_5, 2_0);

显然，使用rangeOfString在类别中实现containsString是微不足道的：

Obviously it's trivial to implement containsString yourself in a category using rangeOfString:

@implementation NSString (Contains)

- (BOOL)myContainsString:(NSString*)other {
  NSRange range = [self rangeOfString:other];
  return range.length != 0;
}

@end

这篇关于NSString包含字符串崩溃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！