关于EnumerateObjectsUsingBlock和for-in之间的较量
2016-05-30 17:18
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遍历一个数组看谁快
参赛选手ForLoop,
For - in,
enumerateObjectsUsingBlock这个三个方法:
NSMutableArray *test = [NSMutableArray array]; for (int i = 0; i < 1000000; i ++) { [test addObject:@(i)]; } __block int sum = 0; double date_s = CFAbsoluteTimeGetCurrent(); for (int i = 0; i < test.count; i ++) { sum += [test[i] integerValue]; } double date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"Sum : %d ForLoop Time: %f ms",sum,date_current * 1000); sum = 0; date_s = CFAbsoluteTimeGetCurrent(); for (NSNumber *num in test) { sum += [num integerValue]; } date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"Sum : %d For-in Time: %f ms",sum,date_current * 1000); sum = 0; date_s = CFAbsoluteTimeGetCurrent(); [test enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) { sum += [obj integerValue]; }]; date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"Sum : %d enumrateBlock Time: %f ms",sum,date_current * 1000);
最后输出如下:
打印输出
For-in方法最快速
结论:
当只是遍历一个数组的时候使用For-in会比较快速, 推荐使用For-in遍历数组.通过Value查找Index看谁快
假如现在我们要查找一个Value, 这个Value 值是100001, 找出它的index (数组的序列号).那么现在我们来比较一下
参赛选手
For - in,
enumerateObjectsUsingBlock,
enumerateObjectsWithOptions这个三个方法: (ForLoop已经不再继续讨论了)
NSMutableArray *test = [NSMutableArray array]; for (int i = 0; i < 10000000; i ++) { [test addObject:@(i + 10)]; } //For-in __block NSInteger index = 0; double date_s = CFAbsoluteTimeGetCurrent(); for (NSNumber *num in test) { if ([num integerValue] == 9999999) { index = [test indexOfObject:num]; break; } } double date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"index : %ld For-in Time: %f ms",(long)index,date_current * 1000); //enumerateObjectsUsingBlock index = 0; date_s = CFAbsoluteTimeGetCurrent(); [test enumerateObjectsUsingBlock:^(id num, NSUInteger idx, BOOL *stop) { if ([num integerValue] == 9999999) { index = idx; *stop = YES; } }]; date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"index : %ld enumerateBlock Time: %f ms",(long)index,date_current * 1000); //enumerateObjectsWithOptions index = 0; date_s = CFAbsoluteTimeGetCurrent(); [test enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id num, NSUInteger idx, BOOL *stop) { if ([num integerValue] == 9999999) { index = idx; *stop = YES; } }]; date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"index : %ld enumerateObjectsWithOptions Time: %f ms",(long)index,date_current * 1000);
最后输出如下图:
打印输出
enumerateObjectsWithOptions方法最快速
结论:
通过Value查询index的时候, 面对大量的数组推荐使用enumerateObjectsWithOptions的并行方法.
For-in和
enumerateObjectsWithOptions方法这里我比较喜欢第二种写法简洁直观.
现在咱们要遍历字典
这里我们比较一下使用For-in和
enumerateKeysAndObjectsUsingBlock这个两个方法:
NSDictionary *testDictionary = @{ @"Auther" : @"yyyyy", @"Game" : @"Dota", @"App" : @"dddddd", @"Market" : @"AppStore" }; //For - in NSMutableArray *forInArry = [NSMutableArray array]; double date_s = CFAbsoluteTimeGetCurrent(); NSArray *keys = [testDictionary allKeys]; for (NSString *key in keys) { NSString *Value = testDictionary[key]; [forInArry addObject:Value]; } double date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"index : %ld For-in Time: %f ms",(long)index,date_current * 1000); //enumerateKeysAndObjectsUsingBlock date_s = CFAbsoluteTimeGetCurrent(); NSMutableArray *enumArry = [NSMutableArray array]; [testDictionary enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) { [enumArry addObject:obj]; }]; date_current = CFAbsoluteTimeGetCurrent() - date_s; NSLog(@"index : %ld For-in Time: %f ms",(long)index,date_current * 1000); NSLog(@"ForInArr: %@",forInArry); NSLog(@"enumArry: %@",enumArry);
打印输出:
打印输出
enumerateKeysAndObjectsUsingBlock胜出
结论:
当我们想遍历字典类型的时候, 推荐使用enumerateKeysAndObjectsUsingBlock
不仅仅是因为速度快, 更是因为代码更优雅和直观.
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