iOS13 [UIViewController presentV

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iOS13默认的presentViewController样式

iOS13默认的presentViewController样式

这种样式显然不能符合我们UI的要求，产生这样的问题是因为我们之前一直忽略了UIModalPresentationStyle这个属性。

typedef NS_ENUM(NSInteger, UIModalPresentationStyle) {
    UIModalPresentationFullScreen = 0,
    UIModalPresentationPageSheet API_AVAILABLE(ios(3.2)) API_UNAVAILABLE(tvos),
    UIModalPresentationFormSheet API_AVAILABLE(ios(3.2)) API_UNAVAILABLE(tvos),
    UIModalPresentationCurrentContext API_AVAILABLE(ios(3.2)),
    UIModalPresentationCustom API_AVAILABLE(ios(7.0)),
    UIModalPresentationOverFullScreen API_AVAILABLE(ios(8.0)),
    UIModalPresentationOverCurrentContext API_AVAILABLE(ios(8.0)),
    UIModalPresentationPopover API_AVAILABLE(ios(8.0)) API_UNAVAILABLE(tvos),
    UIModalPresentationBlurOverFullScreen API_AVAILABLE(tvos(11.0)) API_UNAVAILABLE(ios) API_UNAVAILABLE(watchos),
    UIModalPresentationNone API_AVAILABLE(ios(7.0)) = -1,
    UIModalPresentationAutomatic API_AVAILABLE(ios(13.0)) = -2,
};

@property(nonatomic,assign) UIModalPresentationStyle modalPresentationStyle API_AVAILABLE(ios(3.2));

在iOS13之前的版本中, UIViewController的UIModalPresentationStyle属性默认是UIModalPresentationFullScreen，而在iOS13中变成了UIModalPresentationPageSheet。
所以我们需要在presentViewController时，设置一下UIModalPresentationStyle，就可以达到旧的效果。

    UIViewController *viewController = [[UIViewController alloc] init];
    viewController.modalPresentationStyle = UIModalPresentationFullScreen;
    [self persentViewController:viewController animated:YES completion:nil];

One more thing

如果在每一处presentViewController都设置modalPresentationStyle，显然这不够Cool。所以就有下面的思路。

在项目中创建UIViewController的Category，并且在.m中写入如下部分

#import "UIViewController+LL_Utils.h"
#import <objc/runtime.h>

@implementation UIViewController (Utils)

+ (void)load {
    Method originAddObserverMethod = class_getInstanceMethod(self, @selector(presentViewController:animated:completion:));
    Method swizzledAddObserverMethod = class_getInstanceMethod(self, @selector(LL_presentViewController:animated:completion:));
    method_exchangeImplementations(originAddObserverMethod, swizzledAddObserverMethod);
}

- (void)LL_presentViewController:(UIViewController *)viewControllerToPresent animated:(BOOL)flag completion:(void (^)(void))completion {
    if (@available(iOS 13.0, *)) {
        viewControllerToPresent.modalPresentationStyle = UIModalPresentationFullScreen;
        [self LL_presentViewController:viewControllerToPresent animated:flag completion:completion];
    } else {
        // Fallback on earlier versions
        [self LL_presentViewController:viewControllerToPresent animated:flag completion:completion];
    }
}
@end

到这里已经可以实现旧的PresentViewController的样式，但是不能处理某个或者某类UIViewController避免自动设置modalPresentationStyle，所以就有了下面这个方案。

UIViewController+LL_Utils.h

@interface UIViewController (LL_Utils)

/**
Whether or not to set ModelPresentationStyle automatically for instance, Default is [Class LL_automaticallySetModalPresentationStyle].

@return BOOL
*/
@property (nonatomic, assign) BOOL LL_automaticallySetModalPresentationStyle;

/**
 Whether or not to set ModelPresentationStyle automatically, Default is YES, but UIImagePickerController/UIAlertController is NO.

 @return BOOL
 */
+ (BOOL)LL_automaticallySetModalPresentationStyle;

@end

UIViewController+LL_Utils.m

#import "UIViewController+LL_Utils.h"
#import <objc/runtime.h>

static const char *LL_automaticallySetModalPresentationStyleKey;

@implementation UIViewController (LL_Utils)

+ (void)load {
    Method originAddObserverMethod = class_getInstanceMethod(self, @selector(presentViewController:animated:completion:));
    Method swizzledAddObserverMethod = class_getInstanceMethod(self, @selector(LL_presentViewController:animated:completion:));
    method_exchangeImplementations(originAddObserverMethod, swizzledAddObserverMethod);
}

- (void)setLL_automaticallySetModalPresentationStyle:(BOOL)LL_automaticallySetModalPresentationStyle {
    objc_setAssociatedObject(self, LL_automaticallySetModalPresentationStyleKey, @(LL_automaticallySetModalPresentationStyle), OBJC_ASSOCIATION_ASSIGN);
}

- (BOOL)LL_automaticallySetModalPresentationStyle {
    id obj = objc_getAssociatedObject(self, LL_automaticallySetModalPresentationStyleKey);
    if (obj) {
        return [obj boolValue];
    }
    return [self.class LL_automaticallySetModalPresentationStyle];
}

+ (BOOL)LL_automaticallySetModalPresentationStyle {
    if ([self isKindOfClass:[UIImagePickerController class]] || [self isKindOfClass:[UIAlertController class]]) {
        return NO;
    }
    return YES;
}

- (void)LL_presentViewController:(UIViewController *)viewControllerToPresent animated:(BOOL)flag completion:(void (^)(void))completion {
    if (@available(iOS 13.0, *)) {
        if (viewControllerToPresent.LL_automaticallySetModalPresentationStyle) {
            viewControllerToPresent.modalPresentationStyle = UIModalPresentationFullScreen;
        }
        [self LL_presentViewController:viewControllerToPresent animated:flag completion:completion];
    } else {
        // Fallback on earlier versions
        [self LL_presentViewController:viewControllerToPresent animated:flag completion:completion];
    }
}

@end

Another thing

当然还有一个更简单的方法，直接下载UIViewController+LLUtils并且拖入到项目中，就可以了。