Question

我界定了我自己的精选方法,呼吁将4.2.1(iOS)5.0(iOS)和4.3.2(Simulator)推论下来。但是,它从未要求3.1.3(iPhone 2g)。

原因何在?

P.S. 既然一开始撰写问题,即我想到我的3.1.3个装置,便被关起来。或许这是这种奇怪行为的根源。

更新:复制第1版

@implementation UIView (MyOwnCategory)
- (void)drawRect:(CGRect)rect
{
    const char * function = __FUNCTION__;
    [NSException raise: @"hi!" format: @"%s", function];
}
@end

3.1.3 即便是当一叫<代码>[超级代号:建议]明确时,也从未有例外。

Answer 1

我想写几星期前的方法Swizzling,而“Kevin Ballard”在最后发表评论时,我就是这样做的。

因此,通过解决你的问题。还应当在3月工作:

UIView+Border.h:

#import <Foundation/Foundation.h>
@interface UIView(Border)
@end

<UIView+Border.m:

#import "UIView+Border.h"
#import <QuartzCore/QuartzCore.h>
#import <objc/runtime.h>

@implementation UIView(Border)

- (id)swizzled_initWithFrame:(CGRect)frame
{
    // This is the confusing part (article explains this line).
    id result = [self swizzled_initWithFrame:frame];

    // Safe guard: do we have an UIView (or something that has a layer)?
    if ([result respondsToSelector:@selector(layer)]) {
        // Get layer for this view.
        CALayer *layer = [result layer];
        // Set border on layer.
        layer.borderWidth = 2;
        layer.borderColor = [[UIColor redColor] CGColor];
    }

    // Return the modified view.
    return result;
}

- (id)swizzled_initWithCoder:(NSCoder *)aDecoder
{
    // This is the confusing part (article explains this line).
    id result = [self swizzled_initWithCoder:aDecoder];

    // Safe guard: do we have an UIView (or something that has a layer)?
    if ([result respondsToSelector:@selector(layer)]) {
        // Get layer for this view.
        CALayer *layer = [result layer];
        // Set border on layer.
        layer.borderWidth = 2;
        layer.borderColor = [[UIColor blueColor] CGColor];
    }

    // Return the modified view.
    return result;
}

+ (void)load
{
    // The "+ load" method is called once, very early in the application life-cycle.
    // It s called even before the "main" function is called. Beware: there s no
    // autorelease pool at this point, so avoid Objective-C calls.
    Method original, swizzle;

    // Get the "- (id)initWithFrame:" method.
    original = class_getInstanceMethod(self, @selector(initWithFrame:));
    // Get the "- (id)swizzled_initWithFrame:" method.
    swizzle = class_getInstanceMethod(self, @selector(swizzled_initWithFrame:));
    // Swap their implementations.
    method_exchangeImplementations(original, swizzle);

    // Get the "- (id)initWithCoder:" method.
    original = class_getInstanceMethod(self, @selector(initWithCoder:));
    // Get the "- (id)swizzled_initWithCoder:" method.
    swizzle = class_getInstanceMethod(self, @selector(swizzled_initWithCoder:));
    // Swap their implementations.
    method_exchangeImplementations(original, swizzle);
}

@end

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