Customizing UIView for self-painting

Sometimes we need to self-draw uiview to achieve our own needs, such as drawing a continuous curve according to the coordinate point (stock chart), you need to draw the UIView.

Principle: Inherit the UIView Class (CustomView), and realize the drawrect of CustomView.

First look at the fruit chart:

The code is as follows:

. h

#import <UIKit/UIKit.h>

@interface CustomView: UIView

@end

. m

#import "CustomView.h"

@implementation CustomView

-(ID) initWithFrame: (cgrect) frame{

// rewrite initwithframe , don't forget the following sentence

self = [superinitwithframe: frame];

if (self) {

self. BackgroundColor = [uicolorwhitecolor];

}

return self;

}

// override DrawRect method (no call required), draw the desired image

-(void) DrawRect: (cgrect) rect{

// Get image context, note that the API can only be used in DrawRect

cgcontextref context =uigraphicsgetcurrentcontext(); //context: an area of memory painting that represents it as the current View Canvas on the line.

< Span style= "COLOR: #000000" >    nsdictionary *attribute = [ Nsdictionary dictionarywithobjectsandkeys :[ uifont Systemfontofsize : 15.0f nsfontattributename Uicolor redcolor ),   nsforegroundcolorattributename nil ];

< Span style= "COLOR: #000000" >    [ @ " stock chart " Drawinrect: cgrectmake ( 100 200 80 20 ) withattributes:attribute]; // painting title

// start path

Cgcontextbeginpath(context);

// start point Set point

cgcontextmovetopoint(context,ten, +);

// Next coordinate point

cgcontextaddlinetopoint(context,n, +);

// One more next

cgcontextaddlinetopoint(context, ;

// One more next

cgcontextaddlinetopoint(context, a.);

// Connect coordinate points

Cgcontextstrokepath(context);

}

@end

then, in the view controller that needs to use the view,

Viewdidload add West; The following line of code is possible!

Self . View = [[customviewalloc] initwithframe: [uiscreen Mainscreen]. bounds ];

Customizing UIView for self-painting