适用于 iOS 的类似 CSS 的样式类

Question

我目前正在为我的 iOS 应用程序的本机控件实现一个类似 CSS 的样式引擎，以避免从 plist 中读取一大堆样式属性并将每个样式属性应用到每个控件上。

（编辑：不，我不需要 UIWebView，我需要自定义原生控件。我不想实现纯 CSS，只是看起来像 CSS 的东西并使用简单的 CSS。）

假设我有一个如下结构的 plist：

closeButtonStyle = "background:transparent;font:Georgia/14;textColor:#faa"
titleLabelStyle  = "background:transparent;font:Helvetica/12;textAlignment:left"

您可以轻松想象我在其中填充了什么样的属性。

到目前为止，一切正常，我有一个 UIStyle 类，它解析此类声明并将所有找到的值存储在其 ivars 中；我还在 UIView、UILabel、UIButton 上有类别，...仅声明 -(void)setStyle:(UIStyle *)style 方法。仅当定义了样式变量时，此方法才应用它们。

正如我所说，一切正常。

我唯一的问题是关于样式字符串的解析。我选择使用 NSScanner，但我不确定它是否是最佳选择，想听听您的意见。

作为记录，以下是我实现 UIStyle 的方法：

-- UIStyle.h

typedef struct {
    BOOL frame:1;
    BOOL font:1;
    BOOL textColor:1;
    BOOL backgroundColor:1;
    BOOL shadowColor:1;
    BOOL shadowOffset:1;
    BOOL textAlignment:1;
    BOOL titleEdgeInsets:1;
    BOOL numberOfLines:1;
    BOOL lineBreakMode:1;
} UIStyleFlags;

@interface UIStyle: NSObject {
    UIStyleFlags         _has;
    CGRect               _frame;
    UIFont              *_font;
    UIColor             *_textColor;
    UIColor             *_backgroundColor;
    UIColor             *_shadowColor;
    CGSize               _shadowOffset;
    UITextAlignment      _textAlignment;
    UIEdgeInsets         _titleEdgeInsets;
    NSInteger            _numberOfLines;
    UILineBreakMode      _lineBreakMode;
}

@property (readonly, nonatomic) UIStyleFlags         has;
@property (readonly, nonatomic) CGRect               frame;
@property (readonly, nonatomic) UIFont              *font;
@property (readonly, nonatomic) UIColor             *textColor;
@property (readonly, nonatomic) UIColor             *backgroundColor;
@property (readonly, nonatomic) UIColor             *shadowColor;
@property (readonly, nonatomic) CGSize               shadowOffset;
@property (readonly, nonatomic) UITextAlignment      textAlignment;
@property (readonly, nonatomic) UIEdgeInsets         titleEdgeInsets;
@property (readonly, nonatomic) NSInteger            numberOfLines;
@property (readonly, nonatomic) UILineBreakMode      lineBreakMode;

- (id)initWithString:(NSString *)string;
+ (id)styleWithString:(NSString *)string;
+ (id)styleInDict:(NSDictionary *)dict key:(NSString *)key;

@end

@interface UIView (UIStyle)
- (void)setStyle:(UIStyle *)style;
@end

@interface UILabel (UIStyle)
- (void)setStyle:(UIStyle *)style;
@end

@interface UIButton (UIStyle)
- (void)setStyle:(UIStyle *)style;
@end

-- UIStyle.m

#import "UIStyle.h"

@implementation UIStyle

@synthesize has               = _has;
@synthesize frame             = _frame;
@synthesize font              = _font;
@synthesize textColor         = _textColor;
@synthesize backgroundColor   = _backgroundColor;
@synthesize shadowColor       = _shadowColor;
@synthesize shadowOffset      = _shadowOffset;
@synthesize textAlignment     = _textAlignment;
@synthesize titleEdgeInsets   = _titleEdgeInsets;
@synthesize numberOfLines     = _numberOfLines;
@synthesize lineBreakMode     = _lineBreakMode;

- (id)initWithString:(NSString *)string {
    if ((self = [super init])) {
        _has.frame           = NO;
        _has.font            = NO;
        _has.textColor       = NO;
        _has.backgroundColor = NO;
        _has.shadowColor     = NO;
        _has.shadowOffset    = NO;
        _has.textAlignment   = NO;
        _has.titleEdgeInsets = NO;
        _has.numberOfLines   = NO;
        _has.lineBreakMode   = NO;

        _frame           = CGRectZero;
        _font            = nil;
        _textColor       = nil;
        _backgroundColor = nil;
        _shadowColor     = nil;
        _shadowOffset    = CGSizeZero;
        _textAlignment   = UITextAlignmentLeft;
        _titleEdgeInsets = UIEdgeInsetsZero;
        _numberOfLines   = 1;
        _lineBreakMode   = UILineBreakModeClip;

        NSScanner *scanner = [[NSScanner alloc] initWithString:string];
        NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];

        NSCharacterSet *keyEndSet = [NSCharacterSet characterSetWithCharactersInString:@":"];
        NSCharacterSet *valueEndSet = [NSCharacterSet characterSetWithCharactersInString:@";"];

        while (![scanner isAtEnd]) {
            NSString *key;
            NSString *value;

            [scanner scanUpToCharactersFromSet:keyEndSet intoString:&key];
            [scanner scanCharactersFromSet:keyEndSet intoString:NULL];
            [scanner scanUpToCharactersFromSet:valueEndSet intoString:&value];
            [scanner scanCharactersFromSet:valueEndSet intoString:NULL];

            [dict setValue:value forKey:key];
        }
        [scanner release];

        for (NSString *key in dict) {
            NSString *value = (NSString *)[dict objectForKey:key];

            if ([key isEqualToString:@"frame"]) {
                _frame = CGRectFromString(value);
                _has.frame = YES;
            }

            else if ([key isEqualToString:@"font"]) {
                NSArray *font = [value componentsSeparatedByString:@"/"];
                NSString *fontName = (NSString *)[font objectAtIndex:0];
                CGFloat fontSize = (CGFloat)[(NSString *)[font objectAtIndex:1] floatValue];

                _font = [[UIFont fontWithName:fontName size:fontSize] retain];
                _has.font = YES;
            }

            else if ([key isEqualToString:@"textColor"]) {
                _textColor = [[UIColor colorWithString:value] retain];
                _has.textColor = YES;
            }

            else if ([key isEqualToString:@"backgroundColor"]) {
                _backgroundColor = [[UIColor colorWithString:value] retain];
            }

            else if ([key isEqualToString:@"shadow"]) {
                NSArray *shadow = [value componentsSeparatedByString:@"/"];
                _shadowColor = [[UIColor colorWithString:(NSString *)[shadow objectAtIndex:0]] retain];
                _shadowOffset = CGSizeMake((CGFloat)[(NSString *)[shadow objectAtIndex:1] floatValue], (CGFloat)[(NSString *)[shadow objectAtIndex:2] floatValue]);
                _has.shadowColor = YES;
                _has.shadowOffset = YES;
            }

            else if ([key isEqualToString:@"textAlignment"]) {
                if ([value isEqualToString:@"center"]) {
                    _textAlignment = UITextAlignmentCenter;
                }
                else if ([value isEqualToString:@"right"]) {
                    _textAlignment = UITextAlignmentRight;
                }
                else {
                    _textAlignment = UITextAlignmentLeft;
                }
                _has.textAlignment = YES;
            }

            else if ([key isEqualToString:@"titleEdgeInsets"]) {
                _titleEdgeInsets = UIEdgeInsetsFromString(value);
                _has.titleEdgeInsets = YES;
            }

            else if ([key isEqualToString:@"numberOfLines"]) {
                _numberOfLines = (NSInteger)[value integerValue];
                _has.numberOfLines = YES;
            }

            else if ([key isEqualToString:@"lineBreakMode"]) {
                if ([value isEqualToString:@"character"]) {
                    _lineBreakMode = UILineBreakModeCharacterWrap;
                }
                else if ([value isEqualToString:@"clip"]) {
                    _lineBreakMode = UILineBreakModeClip;
                }
                else if ([value isEqualToString:@"head"]) {
                    _lineBreakMode = UILineBreakModeHeadTruncation;
                }
                else if ([value isEqualToString:@"tail"]) {
                    _lineBreakMode = UILineBreakModeTailTruncation;
                }
                else if ([value isEqualToString:@"middle"]) {
                    _lineBreakMode = UILineBreakModeMiddleTruncation;
                }
                else {
                    _lineBreakMode = UILineBreakModeWordWrap;
                }
                _has.lineBreakMode = YES;
            }
        }

        [dict release];
    }
    return self;
}

- (void)dealloc {
    [_font            release];
    [_textColor       release];
    [_backgroundColor release];
    [_shadowColor     release];
    [super dealloc];
}

+ (id)styleWithString:(NSString *)string {
    return [[[UIStyle alloc] initWithString:string] autorelease];
}

+ (id)styleInDict:(NSDictionary *)dict key:(NSString *)key {
    return [[[UIStyle alloc] initWithString:(NSString *)[dict objectForKey:key]] autorelease];
}

@end


@implementation UIView (UIStyle)
- (void)setStyle:(UIStyle *)style {
    if (style.has.frame) {
        [self setFrame:style.frame];
    }

    if (style.has.backgroundColor) {
        [self setBackgroundColor:style.backgroundColor];
    }
}
@end

@implementation UILabel (UIStyle)
- (void)setStyle:(UIStyle *)style {
    [super setStyle:style];

    if (style.has.font)
        [self setFont:style.font];

    if (style.has.textColor)
        [self setTextColor:style.textColor];

    if (style.has.shadowColor)
        [self setShadowColor:style.shadowColor];

    if (style.has.shadowOffset)
        [self setShadowOffset:style.shadowOffset];

    if (style.has.textAlignment)
        [self setTextAlignment:style.textAlignment];

    if (style.has.numberOfLines)
        [self setNumberOfLines:style.numberOfLines];

    if (style.has.lineBreakMode)
        [self setLineBreakMode:style.lineBreakMode];
}
@end

@implementation UIButton (UIStyle)
- (void)setStyle:(UIStyle *)style {
    [super setStyle:style];

    if (style.has.titleEdgeInsets)
        [self setTitleEdgeInsets:style.titleEdgeInsets];
}
@end

这是最好的方法吗？特别是，我想了解您对代码扫描部分（while (![scanner isAtEnd]) 循环）的意见。

Answer 1

由于这不是标记语言，我更喜欢使用 正则表达式就可以了。

Answer 2

你不能使用 UIWebView< /strong> &使用普通CSS？

这不是比重新发明轮子更简单吗？重新发明轮子可能很有趣，但你可能无法做（或支持）CSS 能够做的很多事情。使用这种方法，您可能也无法利用 iOS 功能...您可能只想重新考虑您的方法。