摘要：NSString *a1 = @"stringTestTwo"; __weak NSString *a2 = a1; NSLog(@"a1:%@", a1); NSLog(@"a2:%@", a2); a1 = nil; ... 阅读全文

摘要：官方文档地址https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/Blocks/Articles/00_Introduction.htmlBlock objects... 阅读全文

摘要：Class clusters are a design pattern that the Foundation framework makes extensive use of. Class clusters group a number of private... 阅读全文

摘要：Core Graphics为你提供了计算变换矩阵的一些方法，所以很少需要直接设置CGAffineTransform的值。除非需要创建一个斜切的变换，Core Graphics并没有提供直接的函数。斜切变换是放射变换的第四种类型，较于平移，旋转和缩放并不常用（这... 阅读全文