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我最近开始学习核心图形以在视图上绘制,但每次调用时setNeedsDisplay,该方法都会运行但不会触发drawRect。在我的项目中,我在视图控制器上有一个视图。该视图包含一个 if 语句,drawRect用于检查 BOOL 变量是 YES 还是 NO。如果是,它使用代码绘制一个红色圆圈。如果否,则绘制一个蓝色圆圈。在 BOOL 的设置器中,它调用setNeedsDisplay. 我在 ViewController 中创建了这个视图类的一个实例并设置了 BOOL 但视图没有重绘。为什么没有调用该方法?我在下面发布了 xcode 文件和代码位。

自定义视图.m:

    #import "CustomView.h"

@implementation CustomView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self setup];
    }
    return self;
}

-(void)awakeFromNib{
    [self setup];
}

-(void)setup{
    _choice1 = YES;
}

-(void)setChoice1:(BOOL)choice1{
    _choice1 = choice1;
    [self setNeedsDisplay];
}


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    if (_choice1) {
        UIBezierPath * redCircle = [UIBezierPath bezierPathWithOvalInRect:rect];
        [[UIColor redColor]setFill];
        [redCircle fill];
    }else if (!_choice1){
        UIBezierPath * blueCircle = [UIBezierPath bezierPathWithOvalInRect:rect];
        [[UIColor blueColor]setFill];
        [blueCircle fill];

    }
}

@end

自定义视图.h:

    #import <UIKit/UIKit.h>

@interface CustomView : UIView

@property (nonatomic) BOOL choice1;

@end

视图控制器.m:

#import "ViewController.h"
#import "CustomView.h"

@interface ViewController ()
- (IBAction)Change:(id)sender;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)Change:(id)sender {
    CustomView * cv = [[CustomView alloc]init];
    [cv setChoice1:NO];
}
@end

完整项目:https ://www.mediafire.com/?2c8e5uay00wci0c

谢谢

4

1 回答 1

1

您需要为您CustomViewViewController. 删除创建新CustomView实例的代码并用于_cv引用 customView。

@interface ViewController ()
- (IBAction)Change:(id)sender;

@property (weak,nonatomic) IBOutlet CustomView *cv;

@end

然后,在情节提要中,将 ViewController 的 cv 出口连接到CustomView. 此外,您需要initFromCoder:CustomView.

- (id)initWithCoder:(NSCoder *)aDecoder {
    if ((self = [super initWithCoder:aDecoder])) {
        [self setup];
    }
    return self;
}
于 2014-04-15T14:54:39.477 回答