CGContextSelectFont等效 [英] CGContextSelectFont equivalent

问题描述

在iOS7中，不推荐使用CGContextSelectFont。弃用消息说我必须使用核心文本，但我不知道这段代码的确切等价：

In iOS7 CGContextSelectFont is deprecated. Deprecation message says that I have to use Core Text, but I don't know which is the exact equivalent of this piece of code:

CGContextSelectFont(context, "Helvetica", kBarLabelSize, kCGEncodingMacRoman);
CGContextSetTextDrawingMode(context, kCGTextFill);
CGContextSetRGBFillColor(context, 0, 0, 0, 1.0);
CGContextSetTextMatrix (context, CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, 0.0));
CGContextShowTextAtPoint(context, barX, barY, [@"Some text" cStringUsingEncoding:NSUTF8StringEncoding], [barValue length]);

我已经能够使用以下代码创建字体：

I've been able to create the font with this code:

CFMutableAttributedStringRef attrStr = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
CTFontRef font = CTFontCreateWithName(CFSTR("Helvetica"), kBarLabelSize, NULL);
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTFontAttributeName, font);

但是现在我可以用这种字体画一个文字到上下文中吗？

But now haw can I "draw" a text with this font into the context?

推荐答案

从我的代码中我可以理解，完全相同的是：

As best I can understand from your code, the exact equivalent is:

CGContextSetTextDrawingMode(context, kCGTextFill); // This is the default
[[UIColor blackColor] setFill]; // This is the default
[@"Some text" drawAtPoint:CGPointMake(barX, barY)
           withAttributes:@{NSFontAttributeName:[UIFont fontWithName:@"Helvetica"
                                                                size:kBarLabelSize]
                            }];

请注意您调用 CGContextSetTextDrawingMode 和 CGContextSetRGBFillColor 正在将值设置为默认值。使用像这样的UIKit绘图时，不需要调用 CGContextSetTextMatrix 。

Note that your calls to CGContextSetTextDrawingMode and CGContextSetRGBFillColor are setting the values to the defaults. Your call to CGContextSetTextMatrix is not needed when using UIKit drawing like this.

我不知道<$ c但是，$ c> [barValue length] 就在这里。我假设您只是错误地将其用于 @Some text的长度。 （ length 不是您需要的字节数。您可能意味着 [barValue lengthOfBytesUsingEncoding：NSUTF8StringEncoding] ）。

I have no idea what [barValue length] is here, however. I'm assuming that you simply incorrectly used this for the length of @"Some text". (length is not the number of bytes which is what you need. What you probably meant was [barValue lengthOfBytesUsingEncoding:NSUTF8StringEncoding]).

请注意，UIKit字符串绘图（此处显示）包装了Core Text。

Note that UIKit string drawing (seen here) wraps Core Text.

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