iOS13 [UIViewController presentViewController]樣式適配

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iOS13默認的presentViewController樣式

這種樣式顯然不能符合咱們UI的要求，產生這樣的問題是由於咱們以前一直忽略了UIModalPresentationStyle這個屬性。

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));
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在iOS13以前的版本中, UIViewController的UIModalPresentationStyle屬性默認是UIModalPresentationFullScreen，而在iOS13中變成了UIModalPresentationPageSheet。 因此咱們須要在presentViewController時，設置一下UIModalPresentationStyle，就能夠達到舊的效果。

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

若是在每一處presentViewController都設置modalPresentationStyle，顯然這不夠Cool。因此就有下面的思路。

在項目中建立UIViewController的Category，而且在.m中寫入以下部分

#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
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到這裏已經能夠實現舊的PresentViewController的樣式，可是不能處理某個或者某類UIViewController避免自動設置modalPresentationStyle，因此就有了下面這個方案。

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
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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
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Another thing

固然還有一個更簡單的方法，直接下載UIViewController+LLUtils而且拖入到項目中，就能夠了。