如何在 iPhone UILabel 中设置字距调整

我正在开发一个 iPhone 应用程序，我想在 UILabel 中设置字距调整。我写的代码（可能围绕kCTKernAttributeName）似乎有错误。我该如何解决这个问题？

NSMutableAttributedString *attStr;   
NSString *str = @"aaaaaaa";    
CFStringRef kern = kCTKernAttributeName;        
NSNumber *num = [NSNumber numberWithFloat: 2.0f];    
NSDictionary *attributesDict = [NSDictionary dictionaryWithObject:num 
forKey:(NSString*)kern];        
[attStr initWithString:str attributes:attributesDict];      
CGRect frame1 = CGRectMake(0, 0, 100, 40);    
UILabel *label1 = [[UILabel alloc] initWithFrame:frame1];    
label1.text = attStr    
[self.view addSubview:label1];

老问题，但你现在就可以（很容易）做到。

NSMutableAttributedString *attributedString;
attributedString = [[NSMutableAttributedString alloc] initWithString:@"Please get wider"];
[attributedString addAttribute:NSKernAttributeName value:@5 range:NSMakeRange(10, 5)];
[self.label setAttributedText:attributedString];

2013 年 11 月，为了扩展这个伟大的答案，这里有一些完全典型的代码。通常你也会设置字体。请注意评论中使用普通旧 .text 的老式方式。希望它可以帮助某人

NSString *yourText = @"whatever";

UILabel* label = [[UILabel alloc] initWithFrame:CGRectMake(0,0,0,0)];

// simple approach with no tracking...
// label.text = yourText;
// [label setFont:[UIFont fontWithName:@"HelveticaNeue-Light" size:24]];

NSMutableAttributedString *attributedString;

attributedString = [[NSMutableAttributedString alloc] initWithString:yourText];

[attributedString addAttribute:NSKernAttributeName
                         value:[NSNumber numberWithFloat:2.0]
                         range:NSMakeRange(0, [yourText length])];

[attributedString addAttribute:NSFontAttributeName
                         value:[UIFont fontWithName:@"HelveticaNeue-Light" size:24]
                         range:NSMakeRange(0, [yourText length])];

label.attributedText = attributedString;

label.textColor = [UIColor blackColor];
label.backgroundColor = [UIColor clearColor];
label.textAlignment = NSTextAlignmentCenter;

[label sizeToFit];