OC版本

[textField setValue:[NSNumber numberWithInt:10] forKey:@"paddingTop"];
    [textField setValue:[NSNumber numberWithInt:10] forKey:@"paddingLeft"];
    [textField setValue:[NSNumber numberWithInt:10] forKey:@"paddingBottom"];
    [textField setValue:[NSNumber numberWithInt:10] forKey:@"paddingRight"];

swift版本

textField?.setValue(NSNumber(value: 10), forKey: "paddingLeft")
設(shè)置textField左邊距10

至于placeholder的邊距，可以在placeholder字符串前加幾個(gè)空格
比如：" 輸入數(shù)字"