** Objective-C 语言是“消息结构”(messaging structure) 类似C++ 、Java 是“函数调用”(function calling)**
// messaging structure (Objective-C)
Object *obj = [Object new];
[obj performWith:parameter1 and:parameter2];
// function calling (C++)
Object *obj = new Object;
obj->perform(parameter1,parameter2);
** Objective-C对象声明 **
// 声明一个名为 someSting 的变量,其类型是 NSString * 。
NSString *someString = @"The String";
// 此 someSting 为指向NSString 的指针。
NSString someString;
// error :interface type cannot be statically allocated
CGRect frame;
frame.origin.x = 0.0f;
frame.origin.y = 10.0f;
frame.size.width = 100.0f;
frame.size.height = 150.0f;
// CGRect 是 C 结构体,其定义是:
struct CGRect {
CGPoint origin;
CGSize size;
};
type struct CGRect CGRect;