iOS 13 适配

随着苹果发布会的开展，iOS 13 也随之而来，又来适配的 work 了，后续会持续更新，欢迎大家发现关于适配的问题，一起来解决它！

1、presentViewController的问题

原因：
主要是因为之前对UIViewController里面的一个属性，即modalPresentationStyle（该属性是控制器在模态视图时将要使用的样式）没有设置需要的类型。
在iOS13中modalPresentationStyle的默认改为UIModalPresentationAutomatic,而在之前默认是UIModalPresentationFullScreen。

解决方案：
只要将modalPresentationStyle设置成UIModalPresentationFullScreen即可解决该问题。

2、私有KVC

原因：
iOS不允许valueForKey、setValue: forKey获取和设置私有属性，需要使用其它方式修改

解决方案：
[textField setValue:[UIColor red] forKeyPath:@"_placeholderLabel.textColor"];
//替换为
textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"输入"attributes:@{NSForegroundColorAttributeName: [UIColor red]}];

为了使用方便，可以给textField添加一个分类，给这个分类添加一个placeholdColor、placeholdFont属性，这样就不用每个对象都写一遍这段代码了。话不多说，直接上代码

@interface UITextField (Add)
/// 占位符的颜色
@property (nonatomic, strong) UIColor *placeholderColor;
/// 占位符的字号
@property (nonatomic, strong) UIFont *placeholdFont;
@end


#import "UITextField+Add.h"

static void *placeholderColorKey = &placeholderColorKey;
static void *placeholderFontKey = &placeholderFontKey;

@implementation UITextField (Add)

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        NSString *oneSelector = NSStringFromSelector(@selector(setPlaceholder:));
        NSString *twoSelector = NSStringFromSelector(@selector(setFont:));
        NSArray *selectors = @[oneSelector, twoSelector];
        [selectors enumerateObjectsUsingBlock:^(NSString *originalString, NSUInteger idx, BOOL * _Nonnull stop) {
            ///交换方法
            NSString *swizzledSelString = [@"hmj_" stringByAppendingString:originalString];
            Method originalMethod = class_getInstanceMethod(self, NSSelectorFromString(originalString));
            Method swizzledMethod = class_getInstanceMethod(self, NSSelectorFromString(swizzledSelString));
            BOOL didAddMethod = class_addMethod(self, NSSelectorFromString(originalString), method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
            if (didAddMethod) {
                class_replaceMethod(self, NSSelectorFromString(swizzledSelString), method_getImplementation(originalMethod), method_getTypeEncoding(swizzledMethod));
            } else {
                method_exchangeImplementations(originalMethod, swizzledMethod);
            }
        }];
    });
}

- (void)hmj_setPlaceholder:(NSString *)placeholder {
    [self sinochem_setPlaceholder:placeholder];
    [self setCustomePlaceholderColorAndFont];
}

- (void)hmj_setFont:(UIFont *)font {
    [self sinochem_setFont:font];
    [self setCustomePlaceholderColorAndFont];
}
// 这个函数是调整placeholder在placeholderLabel中绘制的颜色和字号
- (void)setCustomePlaceholderColorAndFont {
    if (self.placeholder) {
        NSMutableAttributedString *placeholderString = [[NSMutableAttributedString alloc] initWithString:self.placeholder attributes:@{NSForegroundColorAttributeName:self.placeholderColor, NSFontAttributeName:self.placeholdFont}];
        self.attributedPlaceholder = placeholderString;
    }
}

- (void)setPlaceholderColor:(UIColor *)placeholderColor {
    objc_setAssociatedObject(self, &placeholderColorKey, placeholderColor, OBJC_ASSOCIATION_COPY);
}

- (UIColor *)placeholderColor {
    UIColor *placeholderColor = objc_getAssociatedObject(self, &placeholderColorKey);
    if (!placeholderColor) {
        placeholderColor = self.textColor;
    }
    return placeholderColor;
}

- (void)setPlaceholdFont:(UIFont *)placeholdFont {
    objc_setAssociatedObject(self, &placeholderFontKey, placeholdFont, OBJC_ASSOCIATION_COPY);
}

- (UIFont *)placeholdFont {
    UIFont *placeholdFont = objc_getAssociatedObject(self, &placeholderFontKey);
    if (!placeholdFont) {
        placeholdFont = self.font;
    }
    return placeholdFont;
}
@end

注意：此方法设置的默认placeholderColor 和 placeholdFont 分别是self.textColor和self.font，如果有其他需求，可以自行修改。

此文章会持续更新，欢迎大家将发现的iOS 13 问题写到评论区，一起解决。