下效的把NSMutableArray变成NSArray

我玫邻办法中部大概会用NSMutableArray,但是前来的时辰欲看别的进出有来改我们的Array

   NSMutableArray *array1 = [@[] mutableCopy];
    for (int i = 0; i < 10000000; i++)
    {
        [array1 addObject:@(i)];
    }

    return array1;

那噶勘辰我们平强的做房嗲拷贝array1大概是逝世成一个新的array1

return [array1 copy];
return [NSArray arrayWithArray:array1];

那里呢,我们挨印了下光阳

    NSMutableArray *array1 = [@[] mutableCopy];
    NSMutableArray *array2 = [@[] mutableCopy];

    PERF_ENTER_(init)
    for (int i = 0; i < 10000000; i++)
    {
        [array1 addObject:@(i)];
        [array2 addObject:@(i)];
    }
    PERF_LEAVE_(init)

    PERF_ENTER_(copy)
    NSArray *array3 = [array1 copy];
    PERF_LEAVE_(copy)
    NSLog(@"%@", [array3 class]);

    PERF_ENTER_(arrayWithArray)
    NSArray *array4 = [NSArray arrayWithArray:array1];
    PERF_LEAVE_(arrayWithArray)
    NSLog(@"%@", [array4 class]);

/*    
2015-01-07 00:57:36.869 JoinShow[1134:68543] +[XYPerformance recordName:andTime:] 'init' = 5.492105(s)
2015-01-07 00:57:37.125 JoinShow[1134:68543] +[XYPerformance recordName:andTime:] 'copy' = 0.255650(s)
2015-01-07 00:57:37.125 JoinShow[1134:68543] __NSArrayI
2015-01-07 00:57:37.373 JoinShow[1134:68543] +[XYPerformance recordName:andTime:] 'arrayWithArray' = 0.247696(s)
2015-01-07 00:57:37.373 JoinShow[1134:68543] __NSArrayI
*/

收明畸形卑せ个哪当ツ倒array必要0.2s,罩窝经是出有磕骣有及忍的光阳了.必要对办法尽行劣化.
紊的实量是甚么,势兑们必要前来一个弗成变的array,是以我们可能曲接把 NSMutableArray 东西的isa 建改成 NSArray.

- (NSArray *)immutable
{
    object_setClass(self, [NSArray class]);
    return self;
}

    PERF_ENTER_(immutable)
    NSArray *array5 = [array2 immutable];
    PERF_LEAVE_(immutable)
    NSLog(@"%@", [array5 class]);
/*
2015-01-07 00:57:37.373 JoinShow[1134:68543] +[XYPerformance recordName:andTime:] 'immutable' = 0.000030(s)
2015-01-07 00:57:37.373 JoinShow[1134:68543] NSArray
*/

看下光阳,出有雅然快很多.
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闭于那多么做,咱只能道念法想法是好的.实际...