我有一个从NSAttributedString
继承的类,如下所示:
Text.h:
#import <Foundation/Foundation.h>
@interface Text : NSAttributedString
-(id) initWithString:(NSString*) text andFont:(NSFont*)font andLineHeight:(float) lineHeight andLetterSpacing:(float) letterSpacing;
@end
Text.m:
#import "Text.h"
#import <Cocoa/Cocoa.h>
@implementation Text
-(id) initWithString:(NSString*) text andFont:(NSFont*)font andLineHeight:(float) lineHeight andLetterSpacing:(float) letterSpacing
{
NSMutableParagraphStyle* paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setParagraphStyle: [NSParagraphStyle defaultParagraphStyle]];
paragraphStyle.lineHeightMultiple = lineHeight;
NSDictionary* attributes =
@{
NSFontAttributeName: font,
NSKernAttributeName: @(letterSpacing),
NSParagraphStyleAttributeName: paragraphStyle
};
self = [super initWithString:text attributes:attributes];
return self;
}
@end
当我实例化此类时:
[[Text alloc] initWithString:@"Test" andFont:welcomeLabelFont andLineHeight:52 andLetterSpacing:0.0f]];
我得到以下异常:
2017-07-17 17:21:15.771610+0300 Test[41403:10128169] -[Text initWithString:attributes:]: unrecognized selector sent to instance 0x600000000f70
选择器在基类中可用,单击事件ctrl会跳到
NSAttributedText
类。谁能指出我做错了什么?参数不是nil指针,并且该调用似乎合法。唯一看起来很奇怪的是该错误的类名称为Text
而不是NSAttributedString
。 最佳答案
代替子类,使用扩展。像这样
// in NSAttributedString+init.h
//
@interface NSAttributedString (Init)
-(instancetype) initWithString:(NSString*) text andFont:(NSFont*)font andLineHeight:(float) lineHeight andLetterSpacing:(float) letterSpacing;
@end
然后,
// in NSAttributedString+init.m
//
#import "NSAttributedString+init.h"
@implementation NSAttributedString (Init)
-(instancetype) initWithString:(NSString*) text andFont:(NSFont*)font andLineHeight:(float) lineHeight andLetterSpacing:(float) letterSpacing {
// ...
}
将该扩展头导入到要使用便捷初始化程序的任何位置。
关于objective-c - 带有从NSAttributedString继承的类的“无法识别的选择器发送到实例”,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/45146905/