重写UIImageView的image属性

重写UIImageView的image属性

效果:

当你重写了UIImageView的image属性后你就会对UIImageView怎么显示图片了如指掌了:)

源码:

UIImageView.h  +  UIImageView.m

//
//  LiveImageView.h
//  Progress
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface LiveImageView : UIImageView

@property (nonatomic, assign)  CGFloat  duration;

@end

//
//  LiveImageView.m
//  Progress
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "LiveImageView.h"

@interface LiveImageView ()

{
    CALayer  *_Layer;
}

@end

@implementation LiveImageView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self)
    {
        _duration = 0.3f;
        _Layer = self.layer;
    }
    return self;
}

// 重写image的setter与getter方法
@synthesize image = _image;

- (void)setImage:(UIImage *)image
{
    if (_image != image)
    {
        CABasicAnimation *ani = [CABasicAnimation animationWithKeyPath:@"contents"];
        ani.fromValue = (__bridge id)(_image.CGImage);
        ani.toValue   =  (__bridge id)(image.CGImage);
        ani.duration  = _duration;
        _Layer.contents = (__bridge id)(image.CGImage);
        [_Layer addAnimation:ani forKey:nil];
        
        _image = image;
    }
}

- (UIImage *)image
{
    return _image;
}

@end

以下是核心代码:

系统的setter方法绝对是这么写的哦:),亲自测试,因为是backed layer,赋值都是没有显式动画的.

以下地方是改变尺寸的动画代码