在字符串上查找NSArray对象的数量

Question

我想计算我的NSString的NSArray对象。我的NSArray有@"a"，@"w"个对象，我的字符串是@"abcdefgw"。我想知道我的字符串中有@"w"个对象的次数。

Answer 1

您可以使用- (NSArray *)componentsSeparatedByString:(NSString *)separator，但这可能存在边界问题。你也可以像这样使用stringByReplacingOccurrencesOfString:withString:：

NSString *shortString = [myString stringByReplacingOccurrencesOfString:@"w" withString:@""];
return mystring.length-shortString.length;

Answer 2

如果您想要计算子字符串，则必须搜索子字符串，然后每次缩小范围......类似于。

-(NSInteger)occurrencesOfSubstring:(NSString *)substring inString:(NSString *)string
{
    int occurrences =0;

    NSRange searchRange = NSMakeRange(0, [string length]);
    NSRange foundRange;
    do {
        foundRange = [string rangeOfString:substring options:NSCaseInsensitiveSearch range:searchRange];
        if ((foundRange.location != NSNotFound)) {
            occurrences++;
            searchRange.location = foundRange.location+foundRange.length;
            searchRange.length = [string length] - (foundRange.location+foundRange.length);
        }
    }while (foundRange.location != NSNotFound);    

    return occurrences;
}