照片查看器

照片 查看器

/**

用纯代码开发的过程

1.
确定界面元素，要有什么内容

2.
用代码来搭建界面

3.
编写代码

*/

@interface
HMViewController
()

@property
(
nonatomic
,
strong
)
UILabel
*noLabel;

@property
(
nonatomic
,
strong
)
UIImageView
*iconImage;

@property
(
nonatomic
,
strong
)
UILabel
*descLabel;

@property
(
nonatomic
,
strong
)
UIButton
*leftButton;

@property
(
nonatomic
,
strong
)
UIButton
*rightButton;

/**
当前显示的照片索引
*/

@property
(
nonatomic
,
assign
)
int
index;

/**
图片信息的数组
*/

@property
(
nonatomic
,
strong
)
NSArray
*imageList;

@property
(
nonatomic
,
strong
)
Person
*person;

@end

@implementation
HMViewController

/**

懒加载
(
延迟加载
)
，通过
getter
实现

效果：让对象在最需要的时候才创建！

*/

– (
NSArray
*)imageList
{

NSLog
(
@"
读取图像信息
"
);

if
(
_imageList
==
nil
) {


NSString
*path = [[
NSBundle
mainBundle
]
pathForResource
:
@"ImageList"
ofType
:
@"plist"
];


_imageList
= [
NSArray
arrayWithContentsOfFile
:path];

    }

return
_imageList
;
}

#pragma mark –
控件的懒加载

//
在
getter
方法中，不要再使用
self.
否则会重复调用
getter
方法，造成死循环

– (
UILabel
*)noLabel
{

if
(
_noLabel
==
nil
) {

UILabel
*label = [[
UILabel
alloc
]
initWithFrame
:
CGRectMake
(
0
,
20
,
self
.
view
.
bounds
.
size
.
width
,
40
)];


_noLabel
= label;

_noLabel
.
textAlignment
=
NSTextAlignmentCenter
;
        [
self
.
view
addSubview
:
_noLabel
];
    }

return
_noLabel
;
}

– (
UIImageView
*)iconImage
{

if
(
_iconImage
==
nil
) {

CGFloat
imageW =
200
;

CGFloat
imageH =
200
;

CGFloat
imageX = (
self
.
view
.
bounds
.
size
.
width
– imageW) *
0.5
;

CGFloat
imageY =
CGRectGetMaxY
(
self
.
noLabel
.
frame
) +
20
;


_iconImage
= [[
UIImageView
alloc
]
initWithFrame
:
CGRectMake
(imageX, imageY, imageW, imageH)];
        [
self
.
view
addSubview
:
_iconImage
];
    }

return
_iconImage
;
}

– (
UILabel
*)descLabel
{

if
(
_descLabel
==
nil
) {

CGFloat
descY =
CGRectGetMaxY
(
self
.
iconImage
.
frame
);

_descLabel
= [[
UILabel
alloc
]
initWithFrame
:
CGRectMake
(
0
, descY,
self
.
view
.
bounds
.
size
.
width
,
100
)];

_descLabel
.
textAlignment
=
NSTextAlignmentCenter
;


//
需要
Label
具有
“
足够的高度
”
，不限制显示的行数


_descLabel
.
numberOfLines
=
0
;
        [
self
.
view
addSubview
:
_descLabel
];
    }

return
_descLabel
;
}

– (
UIButton
*)leftButton
{

if
(
_leftButton
==
nil
) {

_leftButton
= [[
UIButton
alloc
]
initWithFrame
:
CGRectMake
(
0
,
0
,
40
,
40
)];

CGFloat
centerY =
self
.
iconImage
.
center
.
y
;

CGFloat
centerX =
self
.
iconImage
.
frame
.
origin
.
x
*
0.5
;

_leftButton
.
center
=
CGPointMake
(centerX, centerY);

        [
_leftButton
setBackgroundImage
:[
UIImage
imageNamed
:
@"left_normal"
]
forState
:
UIControlStateNormal
];
        [
_leftButton
setBackgroundImage
:[
UIImage
imageNamed
:
@"left_highlighted"
]
forState
:
UIControlStateHighlighted
];
        [
self
.
view
addSubview
:
_leftButton
];


_leftButton
.
tag
= –
1
;

        [
_leftButton
addTarget
:
self
action
:
@selector
(clickButton:)
forControlEvents
:
UIControlEventTouchUpInside
];
    }

return
_leftButton
;
}

– (
UIButton
*)rightButton
{

if
(
_rightButton
==
nil
) {

_rightButton
= [[
UIButton
alloc
]
initWithFrame
:
CGRectMake
(
0
,
0
,
40
,
40
)];

CGFloat
centerY =
self
.
iconImage
.
center
.
y
;

CGFloat
centerX =
self
.
iconImage
.
frame
.
origin
.
x
*
0.5
;

_rightButton
.
center
=
CGPointMake
(
self
.
view
.
bounds
.
size
.
width
– centerX, centerY);

        [
_rightButton
setBackgroundImage
:[
UIImage
imageNamed
:
@"right_normal"
]
forState
:
UIControlStateNormal
];
        [
_rightButton
setBackgroundImage
:[
UIImage
imageNamed
:
@"right_highlighted"
]
forState
:
UIControlStateHighlighted
];
        [
self
.
view
addSubview
:
_rightButton
];


_rightButton
.
tag
=
1
;

        [
_rightButton
addTarget
:
self
action
:
@selector
(clickButton:)
forControlEvents
:
UIControlEventTouchUpInside
];
    }

return
_rightButton
;
}

/**
在
viewDidLoad
创建界面
*/

– (
void
)viewDidLoad
{
    [
super
viewDidLoad
];



//
显示照片信息

    [
self
showPhotoInfo
];
}

/**

重构的目的：让相同的代码只出现一次

*/

– (
void
)showPhotoInfo
{

//
设置序号


self
.
noLabel
.
text
= [
NSString
stringWithFormat
:
@"%d/%d"
,
self
.
index
+
1
,
5
];


//
设置图像和描述


self
.
iconImage
.
image
= [
UIImage
imageNamed
:
self
.
imageList
[
self
.
index
][
@"name"
]];

self
.
descLabel
.
text
=
self
.
imageList
[
self
.
index
][
@"desc"
];


self
.
rightButton
.
enabled
= (
self
.
index
!=
4
);

self
.
leftButton
.
enabled
= (
self
.
index
!=
0
);
}

//
在
OC
中，很多方法的第一个参数，都是触发该方法的对象！

– (
void
)clickButton:(
UIButton
*)button
{

//
根据按钮调整当前显示图片的索引
?


self
.
index
+= button.
tag
;

    [
self
showPhotoInfo
];
}