OC的cell回收重利用問題

OC的cell提供了一個從隊列取出使用過的cell重複利用的函數

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"1"];

經過這個函數能夠取出被回收的cell，反覆利用，從而在界面拉動的時候節約內存（tableview的cell會在界面可視範圍內對看不見的cell進行回收，不是銷燬）。

可是今天我測試時候故意不從隊列取，而是寫  UITableViewCell *  cell=[[UITableViewCell alloc] init];

，而後觀察左邊內存變化狀況，發如今table拉動的時候並無增長內存。這是怎麼回事，而後我又把celll內存打印了一下

 NSLog(@"%p",cell);   

結果以下：

2015-02-07 15:32:57.922 Hello[3901:117856] 0x78879070
2015-02-07 15:32:57.924 Hello[3901:117856] 0x7887b340
2015-02-07 15:32:57.925 Hello[3901:117856] 0x7887ee20
2015-02-07 15:33:02.210 Hello[3901:117856] 0x78e68c10
2015-02-07 15:33:02.744 Hello[3901:117856] 0x78e68e00
2015-02-07 15:33:09.698 Hello[3901:117856] 0x78e68f90
2015-02-07 15:33:13.476 Hello[3901:117856] 0x78879070
2015-02-07 15:33:17.094 Hello[3901:117856] 0x787792e0
2015-02-07 15:33:19.109 Hello[3901:117856] 0x78782a50
2015-02-07 15:33:20.907 Hello[3901:117856] 0x7887a500
2015-02-07 15:33:28.241 Hello[3901:117856] 0x7876e060
2015-02-07 15:33:28.491 Hello[3901:117856] 0x78782f10
2015-02-07 15:33:28.741 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:29.080 Hello[3901:117856] 0x78dc92d0
2015-02-07 15:33:29.291 Hello[3901:117856] 0x78dc8ee0
2015-02-07 15:33:29.591 Hello[3901:117856] 0x78dcb8b0
2015-02-07 15:33:29.757 Hello[3901:117856] 0x78782a50
2015-02-07 15:33:31.131 Hello[3901:117856] 0x7887f440
2015-02-07 15:33:31.209 Hello[3901:117856] 0x78782a50
2015-02-07 15:33:31.275 Hello[3901:117856] 0x78786f70
2015-02-07 15:33:31.359 Hello[3901:117856] 0x7887a500
2015-02-07 15:33:31.443 Hello[3901:117856] 0x7887f440
2015-02-07 15:33:31.591 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:31.826 Hello[3901:117856] 0x78786f70
2015-02-07 15:33:32.524 Hello[3901:117856] 0x78879070
2015-02-07 15:33:32.758 Hello[3901:117856] 0x7887bbe0
2015-02-07 15:33:32.952 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:33.091 Hello[3901:117856] 0x7887f440
2015-02-07 15:33:33.274 Hello[3901:117856] 0x78786f70
2015-02-07 15:33:33.542 Hello[3901:117856] 0x78879070
2015-02-07 15:33:33.982 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:34.124 Hello[3901:117856] 0x78dc8ee0
2015-02-07 15:33:34.275 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:34.502 Hello[3901:117856] 0x78782820
2015-02-07 15:33:34.674 Hello[3901:117856] 0x78e67e20
2015-02-07 15:33:34.775 Hello[3901:117856] 0x78e6c3c0
2015-02-07 15:33:35.692 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:35.842 Hello[3901:117856] 0x78879070
2015-02-07 15:33:36.042 Hello[3901:117856] 0x78dc8ee0
2015-02-07 15:33:36.325 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:36.476 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:36.642 Hello[3901:117856] 0x78879070
2015-02-07 15:33:36.891 Hello[3901:117856] 0x78dc8ee0
2015-02-07 15:33:39.724 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:40.108 Hello[3901:117856] 0x78e67e20
2015-02-07 15:33:40.375 Hello[3901:117856] 0x78dcabb0
2015-02-07 15:33:40.474 Hello[3901:117856] 0x78e6c440
2015-02-07 15:33:40.557 Hello[3901:117856] 0x78782820
2015-02-07 15:33:40.691 Hello[3901:117856] 0x7866bfe0
2015-02-07 15:33:40.974 Hello[3901:117856] 0x78879070
2015-02-07 15:33:41.606 Hello[3901:117856] 0x78782820
2015-02-07 15:33:42.258 Hello[3901:117856] 0x78782820
2015-02-07 15:33:42.443 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:42.527 Hello[3901:117856] 0x78786f70
2015-02-07 15:33:42.610 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:42.711 Hello[3901:117856] 0x78879070
2015-02-07 15:33:42.844 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:43.010 Hello[3901:117856] 0x78e67e20
2015-02-07 15:33:43.277 Hello[3901:117856] 0x7887f440
2015-02-07 15:33:44.261 Hello[3901:117856] 0x78e6c3c0
2015-02-07 15:33:44.346 Hello[3901:117856] 0x78782820
2015-02-07 15:33:44.411 Hello[3901:117856] 0x78786f70
2015-02-07 15:33:44.513 Hello[3901:117856] 0x78782a50
2015-02-07 15:33:44.613 Hello[3901:117856] 0x787872f0
2015-02-07 15:33:44.762 Hello[3901:117856] 0x78879070
2015-02-07 15:33:44.946 Hello[3901:117856] 0x78782820
2015-02-07 15:33:45.960 Hello[3901:117856] 0x7887f440
2015-02-07 15:33:46.277 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:46.377 Hello[3901:117856] 0x78782820
2015-02-07 15:33:46.477 Hello[3901:117856] 0x78879070
2015-02-07 15:33:46.610 Hello[3901:117856] 0x78dbd8c0
2015-02-07 15:33:46.793 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:47.060 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:47.443 Hello[3901:117856] 0x78879070
2015-02-07 15:33:47.510 Hello[3901:117856] 0x78782820
2015-02-07 15:33:47.576 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:47.677 Hello[3901:117856] 0x78dbd8c0
2015-02-07 15:33:47.810 Hello[3901:117856] 0x787872f0
2015-02-07 15:33:47.993 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:48.894 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:48.993 Hello[3901:117856] 0x78dc8fc0
2015-02-07 15:33:49.161 Hello[3901:117856] 0x78782820
2015-02-07 15:33:49.378 Hello[3901:117856] 0x78dbd8c0
2015-02-07 15:33:49.794 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:50.620 Hello[3901:117856] 0x78879070
2015-02-07 15:33:50.711 Hello[3901:117856] 0x78dc81f0
2015-02-07 15:33:50.794 Hello[3901:117856] 0x78e67060
2015-02-07 15:33:50.894 Hello[3901:117856] 0x78e67e20
2015-02-07 15:33:51.027 Hello[3901:117856] 0x78879070

用工具查找其中幾個地址就會發現有重複的，說明OC已經對這個cell的存取進行了內存優化，即便不從隊列裏面拿去也不會佔用更多內存使用，目前發現是這樣，可是建議仍是繼續用

dequeueReusableCellWithIdentifier 函數，讓程序更可靠。