ios - Objective-C 默认启用自动收缩

Question

是否有可能为 UILabel 和 UIButton 默认启用自动收缩？

基本上，我需要他们运行这段代码:

self.adjustsFontSizeToFitWidth = YES;
self.minimumScaleFactor = 0.5;

即使它们是从 .xib 文件或代码初始化的，也不需要替换为自定义 MyLabel。

Answer 1

尽管我强烈反对(如the question comments 中所述)，但这里有一种方法可以使用method swizzling 实现这一点。和一个 category :

UILabel+SwizzledInitializer.h:

//
//  UILabel+SwizzledInitializer.h
//

#import <UIKit/UIKit.h>

@interface UILabel (SwizzledInitializer)

@end

UILabel+SwizzledInitializer.m:

//
//  UILabel+SwizzledInitializer.m
//

#import "UILabel+SwizzledInitializer.h"
#import <objc/runtime.h>

@implementation UILabel (SwizzledInitializer)

+ (void)load
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];

        SEL originalSelector = @selector(initWithFrame:);
        SEL swizzledSelector = @selector(initWithFrame_swizzledForAutoShrink:);

        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);

        BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));

        if (didAddMethod) {
            class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}

- (instancetype)initWithFrame_swizzledForAutoShrink:(CGRect)frame;
{
    self = [self initWithFrame_swizzledForAutoShrink:frame];
    if (self) {
        self.adjustsFontSizeToFitWidth = YES;
        self.minimumScaleFactor = 0.5;
    }
    return self;
}

@end