dispatch_async(dispatch_get_global_queue(0, 0), ^{    Person *p1 = [[Person alloc] init];    NSMutableArray *array = [NSMutableArray arrayWithCapacity:100000];//   ArrayList   *array = [ArrayList arrayWithCapacity:100000];    CFAbsoluteTime startTime =CFAbsoluteTimeGetCurrent();    for (int i = 0; i<100000; i++) {      [array addObject:p1];    }    CFAbsoluteTime linkTime = (CFAbsoluteTimeGetCurrent() - startTime);    CFTimeInterval duration = linkTime * 1000.0f;    NSLog(@"Linked in %f ms",duration);    [self->_timeArray addObject:@(duration)];    count++;  });NSMutableArray 5.081740292635832 msArrayList 16.27591523257168 ms以下是 ArrayList 的具體實現 ,內部是一個 C語言的數組用來存放對象//// ArrayList.m// ArrayList//// Created by dzb on 2018/7/19.// Copyright © 2018 大兵布萊恩特. All rights reserved.//#import "ArrayList.h"static NSInteger const defaultCapacity = 10;typedef void * AnyObject;@interface ArrayList (){  AnyObject *_array;  NSInteger _size;  NSInteger _capacity;}@end@implementation ArrayList#pragma mark - init- (instancetype)init{  self = [super init];  if (self) {    [self resetArray];  }  return self;}+ (instancetype)array {  return [[ArrayList alloc] initWithCapacity:defaultCapacity];}+ (instancetype)arrayWithCapacity:(NSUInteger)numItems {  return [[ArrayList alloc] initWithCapacity:numItems];}- (instancetype)initWithCapacity:(NSUInteger)numItems {  _capacity = numItems;  _array = calloc(_capacity,sizeof(AnyObject));  _size = 0;  return self;}/** 數組重置 */- (void) resetArray {  _size = 0;  if (_array != NULL)    _array[_size] = NULL;    free(_array);  _capacity = defaultCapacity;  _array = calloc(_capacity, sizeof(AnyObject));}#pragma makr - 增加操作- (void)addObject:(id)anObject {  [self insertObject:anObject atIndex:_size];}- (void)insertObject:(id)anObject atIndex:(NSUInteger)index {  if (!anObject) {    @throw [NSException exceptionWithName:@"add object null." reason:@"object must be not null ." userInfo:nil];    return;  }  ///判越界  if ((index > _size)) {    @throw [NSException exceptionWithName:@"Array is out of bounds" reason:@"out of bounds" userInfo:nil];    return;  }  if (_size == _capacity-1) { ///判斷原來數組是否已經滿了 如果滿了就需要增加數組長度    [self resize:2*_capacity];  }  ///交換索引位置  if (self.count > 0 ) {    for(NSInteger i = _size - 1 ; i >= index ; i--)      _array[i + 1] = _array[i];  }  self->_array[index] = (__bridge_retained AnyObject)(anObject);  _size++;}#pragma mark - 刪除操作- (void)removeAllObjects {  NSInteger i = _size-1;  while (_size > 0) {    [self removeObjectAtIndex:i];    i--;  }  [self resetArray];}- (void)removeObjectAtIndex:(NSUInteger)index {  ///判斷越界  if ((index > _size)) {    @throw [NSException exceptionWithName:@"Array is out of bounds" reason:@"out of bounds" userInfo:nil];    return;  }  AnyObject object =(_array[index]);  CFRelease(object);  for(NSInteger i = index + 1 ; i < _size ; i ++)    _array[i - 1] = _array[i];  _size--;  _array[_size] = NULL;  ///對數組空間縮減  if (_size == _capacity/2) {    [self resize:_capacity/2];  }}- (void)removeObject:(id)anObject {  NSInteger index = [self indexOfObject:anObject];  if (index == NSNotFound) return;  [self removeObjectAtIndex:index];}- (void)removeLastObject {  if ([self isEmpty]) return;  [self removeObjectAtIndex:_size-1];}#pragma mark - 修改操作- (void)replaceObjectAtIndex:(NSUInteger)index withObject:(id)anObject {  if (!anObject) {    @throw [NSException exceptionWithName:@"add object null." reason:@"object must be not null ." userInfo:nil];    return;  }  ///判斷越界  if ((index > _size)) {    @throw [NSException exceptionWithName:@"Array is out of bounds" reason:@"out of bounds" userInfo:nil];    return;  }  _array[index] = (__bridge AnyObject)(anObject);}#pragma mark - 查詢操作- (BOOL) isEmpty {  return (self->_size == 0);}- (BOOL) isFull {  return (self->_size == self->_capacity-1);}- (id)objectAtIndex:(NSUInteger)index {  if ((index > _size)) {    @throw [NSException exceptionWithName:@"Array is out of bounds" reason:@"out of bounds" userInfo:nil];    return nil;  }  if ([self isEmpty]) { return nil; }  AnyObject obj = _array[index];  if (obj == NULL) return nil;  return (__bridge id)(obj);}- (NSUInteger)indexOfObject:(id)anObject {  for (int i = 0; i<_size; i++) {    id obj = (__bridge id)(_array[i]);    if ([anObject isEqual:obj]) return i;  }  return NSNotFound;}- (BOOL)containsObject:(id)anObject {  for (int i = 0; i<_size; i++) {    id obj = (__bridge id)(_array[i]);    if ([anObject isEqual:obj]) return YES;  }  return NO;}- (id)firstObject {  if ([self isEmpty]) return nil;  return (__bridge id _Nullable)(_array[0]);}- (id)lastObject {  if ([self isEmpty]) return nil;  return (__bridge id _Nullable)(_array[_size]);}- (NSUInteger)count {  return _size;}- (NSString *)description {  NSMutableString *string = [NSMutableString stringWithFormat:@"/nArrayList %p : [ /n" ,self];  for (int i = 0; i<_size; i++) {    AnyObject obj = _array[i];    [string appendFormat:@"%@",(__bridge id)obj];    if (i<_size-1) {      [string appendString:@" , /n"];    }  }  [string appendString:@"/n]/n"];  return string;}/** 對數組擴容 @param capacity 新的容量 */- (void) resize:(NSInteger)capacity {  AnyObject *oldArray = _array;  AnyObject *newArray = calloc(capacity, sizeof(AnyObject));  for (int i = 0 ; i<_size; i++) {    newArray[i] = oldArray[i];  }  _array = newArray;  _capacity = capacity;  free(oldArray);}- (void)dealloc{  if (_array != NULL)    [self removeAllObjects];  free(_array);// NSLog(@"ArrayList dealloc");}@end