iOS中将文本内容实现3D效果

在iOS中可以将文本实现3D效果，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，更多详细的解决方案见http://ask.csdn.net/questions/781

.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;
}

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：