（转）iOS 屏幕适配

参考 微信的多屏适配

目前为止，iPhone屏幕尺寸已经有四种：

3.5（inch）：1/3G/3GS/4/4S

4.0（inch）：5/5S/5C

4.7（inch）：6

5.5（inch）：6Plus

看一下iPhone4~6(+)的屏幕高宽比：

iPhone4(s)：分辨率960*640，高宽比1.5 
iPhone5(s)：分辨率1136*640，高宽比1.775 
iPhone6：分辨率1334*750，高宽比1.779 
iPhone6+：分辨率1920*1080，高宽比1.778

可粗略认为iPhone5(s)、6(+)的高宽比是一致的（16:9），即可以等比例缩放。因此可以按宽度适配： 
fitScreenWidth= width*(SCREEN_WIDTH/320) 
这样，共有iPhone3/4/5、6、6+三组宽度，在iPhone6、6+下将按比例横向放大，也就是说我们要适配宽、高、字号大小（如果说Android屏幕适配是地狱一般，那目前来看iPhone屏幕适配还是很美好的）

适配思路

现在产品设计稿有以iPhone5为基准的，也有以iPhone6为基准的，其实没太大影响，因为iPhone5、6、6P的屏幕尺寸比例几乎一样的，所以以iPhone5为基准标注的尺寸，那适配的方法如下：

#define kScreenWidthRatio  (kScreenWidth / 320.0)
#define kScreenHeightRatio (kScreenHeight / 568.0)
#define AdaptedWidthValue(x)  (ceilf((x) * kScreenWidthRatio))
#define AdaptedHeightValue(x) (ceilf((x) * kScreenHeightRatio))

其实就是计算一个比例，然后iPhone6、6P等比放大，这样就保持了iPhone5、6、6P屏幕视觉效果上的一致了。 
控件尺寸思路搞定了，但仅仅控件等比例拉伸，其中的内容也要去适应，例如UILabel的字体大小适应，其实也很简单：

#define kUHSystemFontWithSize(R)     [UIFont fontWithName: kULSystemFont size: (AdaptedWidthValue(R))]

实践 
有了思路之后，实践一下看看效果，首先看一下最终目标效果图： 
置顶 
iOS开发~iPhone6及iPhone6P的UI适配

Demo简介：

1、利用TableView展示数据，其中TableView的headerView是滚动的广告，整体UI布局使用相对布局（Autolayout）；

2、Autolayout用的是代码实现方式，借助与第三方库Masonry；

3、headerView的滚动广告实现是借助于第三方库SDCycleScrollView；

4、图片下载借助与第三方库SDWebImage；

5、UITableViewCell的自适应高度借助与第三方库UITableView+FDTemplateLayoutCell实现。

新建项目

使用Xcode新建项目后，由于使用到很多第三方，所以使用CocoPods，其中修改Podfile：

platform :ios, ‘7.0’ 
pod ‘Masonry’ 
pod ‘SDCycleScrollView’ 
pod ‘UITableView+FDTemplateLayoutCell’ 
pod ‘SDWebImage’

实现TableView 
1、创建TableView，命名为newslistView：

@property (nonatomic, strong) UITableView *newslistView;

具体实现不说了，介绍一下TableView的布局，这里TableView沾满ViewController的View： 

[self.newslistView mas_makeConstraints:^(MASConstraintMaker *make) { 
make.edges.equalTo(self.view); 
}];

2、实现TableViewHeader 

- (void) loadTableViewHeaderView { 
SDCycleScrollView * cycleScrollView = [SDCycleScrollView cycleScrollViewWithFrame:CGRectMake(0, 0, kScreenWidth, AdaptedHeightValue(SDCycleScrollViewHeight)) imageURLStringsGroup:nil]; // 模拟网络延时情景 
cycleScrollView.pageControlAliment = SDCycleScrollViewPageContolAlimentRight; 
cycleScrollView.delegate = self; 
cycleScrollView.showPageControl = YES; 
cycleScrollView.pageControlStyle = SDCycleScrollViewPageContolStyleAnimated; 
cycleScrollView.pageControlAliment = SDCycleScrollViewPageContolAlimentCenter; 
cycleScrollView.dotColor = [UIColor whiteColor]; // 自定义分页控件小圆标颜色 
cycleScrollView.placeholderImage = [UIImage imageNamed:@”detail_top”]; 
[self.view addSubview:cycleScrollView];

cycleScrollView.imageURLStringsGroup = [self.dataDictionary valueForKey:@"advertisement"];

self.newslistView.tableHeaderView = cycleScrollView;
}

这里使用到了 AdaptedHeightValue(SDCycleScrollViewHeight)来适应屏幕尺寸，4/4S设备的TableViewHeader高度就小一些，6和6P的TableViewHeader高度就大一些，因为我们是已5代设备为参考实现的产品设计稿。 
3、实现TableViewCell

#define UI_DEBUG 0

#define ULAppearanceFontSizeMiddle 13
#define ULAppearanceFontSizeSmall  12

NSString  *const NewsListCellIdentifier = @"NewsListCellIdentifier";

static const CGFloat ULNewsListCellNewsimageViewMarginLeft = 10.0;
static const CGFloat ULNewsListCellNewsimageViewWidth = 100.0;
static const CGFloat ULNewsListCellNewsimageViewHeight = 80.0;

static const CGFloat ULNewsListCellTitleLabelMarginTop = 10.0;
static const CGFloat ULNewsListCellTitleLabelMarginLeft = 10.0;
static const CGFloat ULNewsListCellTitleLabelMarginRight = 10.0;
static const CGFloat ULNewsListCellTitleLabelHeight = 20.0;

static const CGFloat ULNewsListCellContentLabelMarginTop = 10.0;
static const CGFloat ULNewsListCellContentLabelMarginBottom = 10.0;

static const CGFloat ULNewsListCellLineViewMarginLeft = 10.0;
static const CGFloat ULNewsListCellLineViewMarginRight = 10.0;
static const CGFloat ULNewsListCellLineViewHeight = 0.5;

@interface NewsListCell ()

@property (nonatomic, strong) UIImageView *newsImageView;
@property (nonatomic, strong) UILabel *titleLabel;
@property (nonatomic, strong) UILabel *contentLabel;
@property (nonatomic, strong) UIView *lineView;

@end

@implementation NewsListCell

- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
    if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
#if UI_DEBUG
        self.contentView.backgroundColor = [UIColor redColor];
#endif
        [self.contentView addSubview:self.newsImageView];
        [self.contentView addSubview:self.titleLabel];
        [self.contentView addSubview:self.contentLabel];
        [self.contentView addSubview:self.lineView];

        [self makeConstraintSubviews];
    }
    return self;
}

- (void) makeConstraintSubviews {
    [self.newsImageView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.equalTo(self.contentView.mas_left).offset(AdaptedWidthValue(ULNewsListCellNewsimageViewMarginLeft));
        make.size.mas_equalTo(CGSizeMake(AdaptedWidthValue(ULNewsListCellNewsimageViewWidth), AdaptedHeightValue(ULNewsListCellNewsimageViewHeight)));
        make.centerY.equalTo(self.contentView.mas_centerY);
    }];

    [self.titleLabel mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self.contentView.mas_top).offset(AdaptedHeightValue(ULNewsListCellTitleLabelMarginTop));
        make.left.equalTo(self.newsImageView.mas_right).offset(AdaptedWidthValue(ULNewsListCellTitleLabelMarginLeft));
        make.right.equalTo(self.contentView.mas_right).offset(-AdaptedWidthValue(ULNewsListCellTitleLabelMarginRight));
        make.height.mas_equalTo(AdaptedHeightValue(ULNewsListCellTitleLabelHeight));
//        make.bottom.equalTo(self.contentLabel.mas_top).offset(-AdaptedHeightValue(ULNewsListCellContentLabelMarginTop));
    }];

    [self.contentLabel mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.right.equalTo(self.titleLabel);
        make.top.equalTo(self.titleLabel.mas_bottom).offset(AdaptedHeightValue(ULNewsListCellContentLabelMarginTop));
        make.bottom.equalTo(self.lineView.mas_bottom).offset(-AdaptedHeightValue(ULNewsListCellContentLabelMarginBottom));
    }];

    [self.lineView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.bottom.equalTo(self.contentView.mas_bottom).offset(-ULNewsListCellLineViewHeight);
        make.left.equalTo(self.contentView.mas_left).offset(AdaptedWidthValue(ULNewsListCellLineViewMarginLeft));
        make.right.equalTo(self.contentView.mas_right).offset(-AdaptedWidthValue(ULNewsListCellLineViewMarginRight));;
        make.height.mas_equalTo(ULNewsListCellLineViewHeight);
    }];
}

- (void)configureWithData:(News *) news {
    [self.newsImageView sd_setImageWithURL:[NSURL URLWithString:news.imageUrl]];
    self.titleLabel.text = news.title;
    self.contentLabel.text = news.content;
}

#pragma mark - Getters

- (UIImageView *) newsImageView {
    if (!_newsImageView) {
        _newsImageView = [[UIImageView alloc] init];
#if UI_DEBUG
        _newsImageView.backgroundColor = [UIColor greenColor];
#endif
    }
    return _newsImageView;
}

- (UILabel *) titleLabel {
    if (!_titleLabel) {
        _titleLabel = [[UILabel alloc] init];
        _titleLabel.font = kUHSystemFontWithSize(ULAppearanceFontSizeMiddle);
        _titleLabel.textColor = [UIColor blackColor];

#if UI_DEBUG
        _titleLabel.backgroundColor = [UIColor lightGrayColor];
#endif
    }
    return _titleLabel;
}

- (UILabel *) contentLabel {
    if (!_contentLabel) {
        _contentLabel = [[UILabel alloc] init];
        _contentLabel.font = kUHSystemFontWithSize(ULAppearanceFontSizeSmall);
        _contentLabel.textColor = [UIColor grayColor];
        _contentLabel.numberOfLines = 0;
        _contentLabel.lineBreakMode = NSLineBreakByWordWrapping;
        _contentLabel.textAlignment = NSTextAlignmentLeft;

#if UI_DEBUG
        _contentLabel.backgroundColor = [UIColor brownColor];
#endif
    }
    return _contentLabel;
}

- (UIView *) lineView {
    if (!_lineView) {
        _lineView = [[UIView alloc] init];
        _lineView.backgroundColor = [UIColor lightGrayColor];
    }
    return _lineView;
}

@end