使用objective-c定制UIView

Question

我想编写一个UIView执行以下操作的自定义:

• 它需要一个图像并将其添加到视图中.
• 它有一种翻转图像的方法.

我想把这个Custom传递UIView给这个iCarousel类:https: //github.com/nicklockwood/iCarousel

如何UIView使用Objective C和Cocoa 创建自定义？

我开始做以下事情:

CItem.h

#import <UIKit/UIKit.h>

@interface CItem : UIView
{
    UIImageView *box;
}

@property (nonatomic, retain) UIImageView * box;


@end

CItem.m

#import "CItem.h"

@implementation CItem

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


- (void)drawRect:(CGRect)rect {
    // Drawing code
    box = [[UIImageView alloc] initWithFrame:CGRectMake(0,0, 240, 240)];

    [box setImage:[UIImage imageNamed:@ "cleaning.png"]];
    [self addSubview:box];
}


@end

Answer 1

你不应该添加你addSubview:的drawRect:.看到这种方法的讨论:

讨论

此方法的默认实现不执行任何操作.使用本机绘图技术(如Core Graphics和UIKit)绘制视图内容的子类应重写此方法并在其中实现其绘图代码.如果视图以其他方式设置其内容,则无需覆盖此方法.例如,如果视图仅显示背景颜色,或者视图使用基础图层对象直接设置其内容,则无需覆盖此方法.同样,如果视图使用OpenGL ES进行绘制,则不应覆盖此方法.

如果您不使用xib文件,则CItem可以添加代码initWithFrame:.

//CItem.h
#import <UIKit/UIKit.h>

@interface CItem : UIView

- (void)flip;

@end

// CItem.m
#import "CItem.h"

@interface CItem()

@property (assign, nonatomic) BOOL displayingPrimary;

@property (strong, nonatomic) UIImageView *primaryView;
@property (strong, nonatomic) UIImageView *secondaryView;

@end

@implementation CItem

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        _primaryView = [[UIImageView alloc] initWithFrame:frame];
        [_primaryView setImage:[UIImage imageNamed:@ "cleaning.jpg"]];
        [self addSubview:_primaryView];

        _secondaryView = [[UIImageView alloc] initWithFrame:frame];
        [_secondaryView setImage:[UIImage imageNamed:@ "adding.jpg"]];
        [self addSubview:_secondaryView];

    }
    return self;
}

- (void)flip
{
    [UIView transitionFromView:(self.displayingPrimary ? self.primaryView : self.secondaryView)
                        toView:(self.displayingPrimary ? self.secondaryView : self.primaryView)
                      duration:1.0
                       options:(self.displayingPrimary ? UIViewAnimationOptionTransitionFlipFromRight :
                                UIViewAnimationOptionTransitionFlipFromLeft) | UIViewAnimationOptionShowHideTransitionViews
                    completion:^(BOOL finished) {
                        if (finished) {
                            self.displayingPrimary = !self.displayingPrimary;
                        }
                    }];
}

@end

然后你可以CItem像这样使用:

CItem *subView = [[CItem alloc] initWithFrame:CGRectMake(0, 0, 320, 400)];
[self.view addSubview:subView];