[討論] retain count值

看板MacDev作者denru01 (阿儒)時間15年前 (2009/12/26 21:57)推噓1(1推 0噓 6→)

留言7則, 3人參與討論串1/1

今天在寫iPhone程式時，出現一個奇怪的Bug，執行到一半就會當機。找了很久發現問題出在retain count。因為retain count變為0，東西被dealloc了。接下來取用就會出問題。但我不曉得為什麼這樣retain count會變為0，跟大家討論一下。以下只取用重點部分：在.h中 ... NSMutableArray *currentStroke; .... @property (nonatomic, retain) NSMutableArray *currentStroke; 在.m中 @synthesize currentStroke; NSMutableArray *mutableArray = [[NSMutableArray alloc] initWithCapacity:20]; NSLog(@"mutable array retain count1 = %d", [mutableArray retainCount]); currentStroke = mutableArray; NSLog(@"mutable array retain count2 = %d", [mutableArray retainCount]); NSLog(@"currentStroke retain count1 = %d", [currentStroke retainCount]); [currentStroke retain]; NSLog(@"currentStroke retain count2 = %d", [currentStroke retainCount]); 跑出來的結果 2009-12-26 21:52:38.950 [17246:207] mutable array retain count1 = 1 2009-12-26 21:52:38.951 [17246:207] mutable array retain count2 = 1 2009-12-26 21:52:38.951 [17246:207] currentStroke retain count1 = 1 2009-12-26 21:52:38.952 [17246:207] currentStroke retain count2 = 2 我的想法是 mutable array retain count1是1沒錯，但mutable array retain count2應該為2，因為currentStroke的Setter會先release舊的(沒有東西)，再retain新的 (mutableArray)，這時為1+1=2. 後面的retain只是想確定用NSLog輸出的東西正確。請問我的想法哪裡錯了呢？我是用Simulator - 3.1.2 | Debug. 謝謝！ -- ▂▃▄▃▂ ◢ ˙ ◣ ˙ ▅ ▉▃ /◤ 喵喵~~~~ ▊▏◣╲ˍ ╱▎ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 59.126.4.1