IOS中的文本实现3D效果

我想要在IOS中对一些文本进行3D效果渲染，使用了UIKit和标准视图控制器。

实现之的效果大概能成为这样：

能不能通过iOS和UIKit实现？我只用了一个静态PNG图片，文本内容根据用户数据变化。

我的方法是，不断的重复画文本的layer,创建有层次的效果：

我是创建UIImage Category,命名为UIImage+3d,

.h文件：

//
//  UIImage+3D.h
//
//  Created by Lefteris Haritou on 12/10/12.
//  Feel Free to use this code, but please keep the credits
//

#import <UIKit/UIKit.h>

@interface UIImage (Extensions)

+ (UIImage *)create3DImageWithText:(NSString *)_text Font:(UIFont*)_font ForegroundColor:(UIColor*)_foregroundColor ShadowColor:(UIColor*)_shadowColor outlineColor:(UIColor*)_outlineColor depth:(int)_depth;

@end

.m文件：

//
//  UIImage+3D.m
//
//  Created by Lefteris Haritou on 12/10/12.
//  Feel Free to use this code, but please keep the credits
//

#import "UIImage+3D.h"

@implementation UIImage (Extensions)

+ (UIImage *)create3DImageWithText:(NSString *)_text Font:(UIFont*)_font ForegroundColor:(UIColor*)_foregroundColor ShadowColor:(UIColor*)_shadowColor outlineColor:(UIColor*)_outlineColor depth:(int)_depth {

    //calculate the size we will need for our text
    CGSize expectedSize = [_text sizeWithFont:_font constrainedToSize:CGSizeMake(MAXFLOAT, MAXFLOAT)];

    //increase our size, as we will draw in 3d, so we need extra space for 3d depth + shadow with blur
    expectedSize.height+=_depth+5;
    expectedSize.width+=_depth+5;

    UIColor *_newColor;

    UIGraphicsBeginImageContextWithOptions(expectedSize, NO, [[UIScreen mainScreen] scale]);
    CGContextRef context = UIGraphicsGetCurrentContext();

    //because we want to do a 3d depth effect, we are going to slightly decrease the color as we move back
    //so here we are going to create a color array that we will use with required depth levels
    NSMutableArray *_colorsArray = [[NSMutableArray alloc] initWithCapacity:_depth];

    CGFloat *components =  (CGFloat *)CGColorGetComponents(_foregroundColor.CGColor);

    //add as a first color in our array the original color
    [_colorsArray insertObject:_foregroundColor atIndex:0];

    //create a gradient of our color (darkening in the depth)
    int _colorStepSize = floor(100/_depth);

    for (int i=0; i<_depth; i++) {

        for (int k=0; k<3; k++) {
            if (components[k]>(_colorStepSize/255.f)) {
                components[k]-=(_colorStepSize/255.f);
            }
        }        
        _newColor = [UIColor colorWithRed:components[0] green:components[1] blue:components[2] alpha:CGColorGetAlpha(_foregroundColor.CGColor)];

        //we are inserting always at first index as we want this array of colors to be reversed (darkest color being the last)
        [_colorsArray insertObject:_newColor atIndex:0];
    }

    //we will draw repeated copies of our text, with the outline color and foreground color, starting from the deepest
    for (int i=0; i<_depth; i++) {

        //change color
        _newColor = (UIColor*)[_colorsArray objectAtIndex:i];

        //draw the text
        CGContextSaveGState(context);

        CGContextSetShouldAntialias(context, YES);        

        //draw outline if this is the last layer (front one)
        if (i+1==_depth) {
            CGContextSetLineWidth(context, 1);
            CGContextSetLineJoin(context, kCGLineJoinRound);

            CGContextSetTextDrawingMode(context, kCGTextStroke);
            [_outlineColor set];
            [_text drawAtPoint:CGPointMake(i, i) withFont:_font];
        }

        //draw filling        
        [_newColor set];

        CGContextSetTextDrawingMode(context, kCGTextFill);

        //if this is the last layer (first one we draw), add the drop shadow too and the outline
        if (i==0) {
            CGContextSetShadowWithColor(context, CGSizeMake(-2, -2), 4.0f, _shadowColor.CGColor);
        }
        else if (i+1!=_depth){
            //add glow like blur
            CGContextSetShadowWithColor(context, CGSizeMake(-1, -1), 3.0f, _newColor.CGColor);
        }

        [_text drawAtPoint:CGPointMake(i, i) withFont:_font];
        CGContextRestoreGState(context);        
    }

    UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return finalImage;
}


@end

导入category扩展然后如下使用：

UIImage *my3dImage = [UIImage create3DImageWithText:@"3" Font:[UIFont systemFontOfSize:250] ForegroundColor:[UIColor colorWithRed:(200/255.f) green:(200/255.f) blue:(200/255.f) alpha:1.0] ShadowColor:[UIColor blackColor] outlineColor:[UIColor colorWithRed:(225/255.f) green:(225/255.f) blue:(225/255.f) alpha:1.0] depth:8];
UIImageView *imgView = [[UIImageView alloc] initWithImage:my3dImage];
[self.view addSubview: imgView];

图片效果：

我可以提供一个方法，首先画两次字体，稍微改变大小和位置，根据待处理的字体大小可能还要用到fontSize, fontSizeDelta和fontOffset。

出现的效果图大概这样：

代码如下：

- (UIImage *)imageWith3dString:(NSString *)text
{
    CGFloat fontSize = 150.0;
    CGFloat fontSizeDelta = 3.0;
    CGFloat fontOffset = 5.0;

    NSString *fontName = @"Bebas";
    UIFont *font = [UIFont fontWithName:fontName size:fontSize];
    CGSize textSize = [text sizeWithFont:font
                       constrainedToSize:CGSizeMake(CGFLOAT_MAX, CGFLOAT_MAX)];

    CGSize size = CGSizeMake(textSize.width, fontSize);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef ctx = CGBitmapContextCreate(NULL,
                                             (int)size.width,
                                             (int)size.height,
                                             8,
                                             (int)(4 * size.width),
                                             colorSpace,
                                             kCGImageAlphaPremultipliedLast);

    // Draw with shadow
    CGContextSetShadowWithColor(ctx, CGSizeMake(0, 0), 10.0, [UIColor colorWithWhite:0.0 alpha:0.6].CGColor);

    CGContextSetRGBStrokeColor(ctx, 1.0, 1.0, 1.0, 0.6);
    CGContextSetAllowsAntialiasing(ctx, YES);  
    CGContextSetLineWidth(ctx, 2.0);
    CGContextSetTextDrawingMode(ctx, kCGTextFillStroke);

    CGContextSetRGBFillColor(ctx, 222 / 255.0, 222 / 255.0, 222 / 255.0, 1.0);
    CGContextSetCharacterSpacing(ctx, 2.6);
    CGContextSelectFont(ctx, [fontName UTF8String], fontSize - fontSizeDelta, kCGEncodingMacRoman);
    CGContextShowTextAtPoint(ctx, 0.0, 3.0 + fontOffset, [text UTF8String], text.length);

    CGContextSetShadowWithColor(ctx, CGSizeZero, 0.0, NULL); // disable shadow
    CGContextSetCharacterSpacing(ctx, 1.0);
    CGContextSelectFont(ctx, [fontName UTF8String], fontSize, kCGEncodingMacRoman);
    CGContextShowTextAtPoint(ctx, 0.0, 3.0, [text UTF8String], text.length);


    CGImageRef imageRef = CGBitmapContextCreateImage(ctx);
    UIImage *image = [UIImage imageWithCGImage:imageRef];

    CGColorSpaceRelease(colorSpace);
    CGImageRelease(imageRef);
    CGContextRelease(ctx);

    return image;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIImageView *imageView = [[UIImageView alloc] initWithImage:[self imageWith3dString:@"3"]];

    [self.view addSubview:imageView];
}