ARC:使用contextInfo测试案例保留__bridge与__bridge_retain
考虑以下ARC代码: -(void)主要{NSString * s = [[[NSString alloc] initWithString:@"s"];[NSApp beginSheet:sheetmodalForWindow:窗口modalDelegate:自我didEndSelector:@selector(sheetDidEnd:returnCode:context :)contextIn
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