下面的代码崩溃了,但是注释没有崩溃:
@property (retain) NSDate *lastCurrentDate;
...
@synthesize lastCurrentDate;
- (void)viewWillAppear:(BOOL)animated {
BOOL crash = [lastCurrentDate isEqualToDate:[NSDate date]]);
}
- (void)viewDidDisappear:(BOOL)animated {
//lastCurrentDate = [[NSDate date] retain];
lastCurrentDate = [NSDate date];
}
为什么retain属性在objectiveC中不一定保留?