UI_APPEARANCE_SELECTOR是否需要？

Question

對於下面的代碼來說，我們通常應該在TestView.h中用UI_APPEARANCE_SELECTOR定義一個aFont屬性。但是，它似乎並不是必需的。我嘗試了和沒有UI_APPEARANCE_SELECTOR，結果是一樣的。

我不知道這是對還是錯？

[[TestView appearance] setAFont：[UIFont boldSystemFontOfSize：20.0f]];

#import "ViewController.h" 
#import "TestView.h" 
@interface ViewController() 

@end 

@implementation ViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view, typically from a nib. 
    [[TestView appearance] setAFont:[UIFont boldSystemFontOfSize:20.0f]]; 
} 

-(void)viewWillAppear:(BOOL)animated{ 
    [super viewWillAppear:animated]; 

} 

- (void)didReceiveMemoryWarning { 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

@end 

TestView.h

#import <UIKit/UIKit.h> 

@interface TestView : UIView 
@property (strong,nonatomic) UIFont *aFont ; 
@end 

TestView.m

#import "TestView.h" 

@implementation TestView 
{ 
    UILabel *aTestLabel; 
} 
@synthesize aFont=_aFont; 

- (void)drawRect:(CGRect)rect { 
    // Drawing code 
    NSLog(@"A Font= %@ ",_aFont); 
} 


-(id) init{ 
    self=[super init]; 
    if(self){ 
     [self addLabel]; 
    } 
    return self; 
} 

-(id) initWithCoder:(NSCoder *)aDecoder{ 
    self=[super initWithCoder:aDecoder]; 
    if(self){ 
     [self addLabel]; 
    } 
    return self; 
} 

-(void)addLabel{ 
    aTestLabel=[[UILabel alloc] initWithFrame:self.bounds]; 
    aTestLabel.text=@"Hello"; 
    _aFont=[UIFont systemFontOfSize:10.0]; 

    [self addSubview:aTestLabel]; 
} 

-(void)setAFont:(UIFont *)aFont{ 
    _aFont=aFont; 
    aTestLabel.font=_aFont;  
} 

Answer 1

你並不需要使用UIAppearance協議，除非你想控制子視圖你沒有編碼自己的觀點，或者你想控制一個外觀系統廣泛。這裏不需要。只需直接設置字體。

在TestView.m做這樣的事情：

- (void)setAFont:(UIFont *)font 
{ 
    _aFont = font; 
    self.aTestLabel.font = _aFont; 
}