摘要： strong，weak和unsafe_unretain都是用来描述属性的存储特性的。下面通过实例来介绍一下他们的区别：strong：@property (nonatomic, strong) NSString* string1;@property (nonatomic, strong) NSString* string2;self.string1 = @"string1";self.string2 = self.string1;self.string1 = nil;NSLog(@"string 2 = %@",self.string2);显示结果： st 阅读全文