[Objective-C basic tutorial note ch03] (4) oop in oC

1. Steps for declaring a class interface:

1. Declare a class interface and add the class name with @ interfacekeyword.

2. Use {instance variable} to define various data members.

3. method declaration: declare a C function using the infix syntax and use the colon :.

Ii. Declaration class interface instance:

// Declare the circular circle class interface @ interface circle: nsobject {shapecolor fillcolor; // after each new circle object is created, the object contains the two elements-class instance variable shaperect bounds;} // specify the instance variable-(void) setfillcolor: (shapecolor) fillcolor; // method declaration, infix-(void) setbounds: (shaperect) bounds;-(void) draw; @ end // statement of the circle completion class

Iii. Implementation steps

1. Use [email protected] to add the class name

2. Compile the method body {method body} For the method declared in the implementation class }.

IV. Implementation instances

@ Implementation circle // class implementation-(void) setfillcolor: (shapecolor) c {fillcolor = C ;}// setfillcolor-(void) setbounds: (shaperect) B {bounds = B;} // setbounds-(void) Draw {nslog (@ "drawing a circle at (% d) in % @", bounds. x, bounds. y, bounds. width, bounds. height, colorname (fillcolor);} // Implementation of the draw @ end // circle completion class

5. Case study-geometric drawing and fill color

//// Main. M // shapes-object // created by Jason on 14-6-10. // copyright (c) 2014 jasonapp. all rights reserved. // # import <Foundation/Foundation. h> // define different color typedef Enum {kredcolor, kgreencolor, kbluecolor} shapecolor; // define a rectangle to specify the drawing area typedef struct {int x, y, width, height;} shaperect; // converts the incoming color value and returns the nsstring literal nsstring * colorname (shapecolor color) {Switch (color) {Case kredcolor: return @ "red"; break; Case kgreencolor: Return @ "green"; break; Case kbluecolor: Return @ "blue"; break;} return @ "no clue ";} // colorname // declare the circular circle class interface @ interface circle: nsobject {shapecolor fillcolor; // after each new circle object is created, the object contains the two elements-class instance variable shaperect bounds;} // specify the instance variable-(void) setfillcolor: (shapecolor) fillcolor; // method declaration, infix-(void) setbounds: (shaperect) bounds;-(void) draw; @ end // The Declaration of the circle completion class @ implementation circle // class implementation-(void) setfillcolor: (shapecolor) c {fillcolor = C;} // setfillcolor-(void) setbounds: (shaperect) B {bounds = B;} // setbounds-(void) Draw {nslog (@ "drawing a circle at (% d) in % @ ", bounds. x, bounds. y, bounds. width, bounds. height, colorname (fillcolor);} // draw @ end // Implementation of the circle completion class // defines the rectangle @ interface rectangle: nsobject {shapecolorfillcolor; shaperectbounds;}-(void) setfillcolor: (shapecolor) fillcolor;-(void) setbounds: (shaperect) bounds;-(void) draw; @ end // rectangle @ implementation rectangle-(void) setfillcolor: (shapecolor) c {fillcolor = C;} // setfillcolor-(void) setbounds: (shaperect) B {bounds = B;} // setbounds-(void) draw {nslog (@ "drawing a rectangle at (% d) in % @", bounds. x, bounds. y, bounds. width, bounds. height, colorname (fillcolor);} // draw @ end // rectangle // define oblatesphereoids @ interface identifier: nsobject {shapecolorfillcolor; shaperectbounds;}-(void) setfillcolor: (shapecolor) fillcolor;-(void) setbounds: (shaperect) bounds;-(void) draw; @ end // signature @ implementation oblatesphereoid-(void) setfillcolor: (shapecolor) c {fillcolor = C;} // setfillcolor-(void) setbounds: (shaperect) B {bounds = B;} // setbounds-(void) draw {nslog (@ "drawing an egg at (% d) in % @", bounds. x, bounds. y, bounds. width, bounds. height, colorname (fillcolor);} // draw @ end // oblatesphereoid // defines the triangle @ interface triangle: nsobject {shapecolorfillcolor; shaperectbounds;}-(void) setfillcolor: (shapecolor) fillcolor;-(void) setbounds: (shaperect) bounds;-(void) draw; @ end // triangle @ implementation triangle-(void) setfillcolor: (shapecolor) c {fillcolor = C;} // setfillcolor-(void) setbounds: (shaperect) B {bounds = B;} // setbounds-(void) draw {nslog (@ "drawing a triangle at (% d) in % @", bounds. x, bounds. y, bounds. width, bounds. height, colorname (fillcolor);} // draw @ end // triangle // draw the void drawshapes (ID shapes [], int count) {for (INT I = 0; I <count; I ++) {ID shape = shapes [I]; [shape draw] ;}// drawshapesint main (INT argc, const char * argv []) {ID shapes [4]; shaperect rect0 = {0, 0, 10, 30}; shapes [0] = [circle new]; [shapes [0] setbounds: rect0]; [shapes [0] setfillcolor: kredcolor]; shaperect rect1 = {30, 40, 50, 60}; shapes [1] = [rectangle new]; [shapes [1] setbounds: rect1]; [shapes [1] setfillcolor: kgreencolor]; shaperect rect2 = {15, 19, 37, 29}; shapes [2] = [oblatesphereoid new]; [shapes [2] setbounds: rect2]; [shapes [2] setfillcolor: kbluecolor]; shaperect rect3 = {47, 32, 80, 50 }; shapes [3] = [triangle new]; [shapes [3] setbounds: rect3]; [shapes [3] setfillcolor: kredcolor]; drawshapes (shapes, 4 ); return (0 );}

Vi. Summary

1. Procedural programming-"function first, data second"

2. Oop -- "data first, function second"

3. "open/close principle"-the software entity should be open to expansion and closed to changes

4. The private method does not exist in objective-C.

5. Objective-C is responsible for executing important tasks, such as sending messages to objects and passing the number of workers, to support application execution.

6. instantiate an object-send a new message to the corresponding class to create an object.