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a.concepts explain:object: which is created from struct or class templateinstance: which is just used to declare a reference of class or struct it was... 阅读全文
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Visual Format Language short cut in VFLa. NSLayoutConstraint.constraintsWithVisualFormat("formatString", options:[NSLayoutFormatOptions], metrics:[Str... 阅读全文
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English:Category: in Objective-c Category can be used to add extra method to the class, but without property.Extension: in swift we can use extension ... 阅读全文
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这两个操作符都是严格意义上的相等与不相等，意思就是说光是值相等还不行，连内存地址都得一样，因此常用于饮用类型的比较（如class和block） 阅读全文