Question

为什么我会得到一个＆＃39; NSString *＆＃39;丢弃第三行上的currentTextB上的限定符＆＃34; CFAttributedStringSetAtribute（currentTextB ...＆＃34;

CFAttributedStringRef currentTextB = CFAttributedStringCreate(NULL, stringRef, NULL);

CTFontRef font = CTFontCreateWithName((CFStringRef)@"Helvetica", 10.0f, nil);
CFAttributedStringSetAttribute(currentTextB,CFRangeMake(0, strLength-1),kCTFontAttributeName,font);

Answer 1

CFAttributedStringSetAttribute()的第一个参数必须是 mutable 属性字符串。例如：

CFStringRef stringRef = CFSTR("foo");

// Create mutable attributed string from CFStringRef:
CFMutableAttributedStringRef currentTextB = CFAttributedStringCreateMutable(NULL, 0);
CFAttributedStringReplaceString(currentTextB, CFRangeMake(0, 0), stringRef);

// Set an attribute:
CTFontRef font = CTFontCreateWithName(CFSTR("Helvetica"), 10.0f, NULL);
CFAttributedStringSetAttribute(currentTextB,
                               CFRangeMake(0, CFAttributedStringGetLength(currentTextB)),
                               kCTFontAttributeName,font);

或者，使用基础类型NSMutableAttributedString 是CFMutableAttributedStringRef的“免费桥接”，因此可以使用可互换：

NSString *string = @"foo";
NSMutableAttributedString *currentTextB = [[NSMutableAttributedString alloc] initWithString:string attributes:nil];
NSFont *font = [NSFont fontWithName:@"Helvetica" size:10.0];
[currentTextB addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, [string length])];

NSString *丢弃限定符

1 个答案: