sscanf的等效在Objective-C [英] Sscanf Equivalent in Objective-C

问题描述

我目前正在写一个波前的OBJ装载机在Objective-C，我试图找出如何从一个NSString以类似的方式分析数据，在C的sscanf（）函数。

I'm currently writing a wavefront OBJ loader in Objective-C and I'm trying to figure out how to parse data from an NSString in a similar manner to the sscanf() function in C.

OBJ文件中定义的面孔在X，Y，顶点的Z-三胞胎，纹理坐标和法线如：

OBJ files define faces in x,y,z triplets of vertices, texture coordinates, and normals such as:

f 1.43//2.43 1.11//2.33 3.14//0.009

我不关心纹理坐标在当前时刻。在C语言中，一个简单的方法来分析这条线将是一条语句，如：

I'm not concerned about texture coordinates at the current moment. In C, an easy way to parse this line would be a statement such as:

sscanf(buf, "f %d//%d %d//%d %d//%d", &temp[0], &temp[1], &temp[2], &temp[3], &temp[4], &temp[5]);

显然，NS​​String的不能用在的sscanf（）没有首先将它们转换为C风格字符串，但我不知道是否有一个更优雅的方式来进行这种没有做这样的转换。

Obviously, NSStrings can't be used in a sscanf() without first converting them to a C-style string, but I'm wondering if there's a more elegant way to performing this without doing such a conversion.

推荐答案

的<一个href="https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSScanner_Class/Reference/Reference.html">NSScanner类可以在串解析数字，虽然不能被用作下拉更换为sscanf的

The NSScanner class can parse numbers in strings, although it can't be used as a drop-in replacement for sscanf.

修改：这是使用它的方法之一。你也可以把 / 成字符被跳过列表。

Edit: here's one way to use it. You can also put the / into the list of characters to be skipped.

float temp[6];
NSString *objContent = @"f 1.43//2.43 1.11//2.33 3.14//0.009";
NSScanner *objScanner = [NSScanner scannerWithString:objContent];

// Skip the first character.
[objScanner scanString:@"f " intoString:nil];

// Read the numbers.
NSInteger index=0;
BOOL parsed=YES;
while ((index<6)&&(parsed))
{
    parsed=[objScanner scanFloat:&temp[index]];
    // Skip the slashes.
    [objScanner scanString:@"//" intoString:nil];

    NSLog(@"Parsed %f", temp[index]);
    index++;
}

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