xcode-NSMutableArray對象的索引

NSMutableArray對象的索引

NSMutableArray 中的對象是這樣： “0,1,0,1,1,1,0,0”

然後我要獲取所有值為“ 1 ”的對象的索引。

for (NSString *substr in activeItems){
            if ([substr isEqualToString:@"1"]){
                NSLog(@"%u",[activeItems indexOfObject:substr]);   
            }
    }

但是根據文檔說明中方法indexOfObject是返回最低索引值，那麼我應該怎麼獲取值為 “1” 的對象索引呢？

最佳回答：

這個可以通過設置range來解決.

NSRange range = NSMakeRange(0, activeItems.count);
for (NSString *substr in activeItems)
{
    if ([substr isEqualToString:@"1"])
    {
        NSInteger index = [activeItems indexOfObject:substr inRange:range];
        NSLog(@"the object indix is: %d", index);
        range.location = ++index;
        range.length = activeItems.count - index;
    }
}

當然,這種對collection的過濾操作,我建議用NSPredicate.不過你這個過濾也不算復雜,怎樣都行.
不過我還是給你寫出來方法.

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES '1'"];
NSArray *resAry = [activeItems filteredArrayUsingPredicate:predicate];
NSRange range = NSMakeRange(0, activeItems.count);

for (NSString *substr in resAry)
{
    NSInteger index = [activeItems indexOfObject:substr inRange:range];
    NSLog(@"the object indix is: %d", index);
    range.location = ++index;
    range.length = activeItems.count - index;
}